# Roman numerals/Encode

Roman numerals/Encode
You are encouraged to solve this task according to the task description, using any language you may know.

Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero.

In Roman numerals:

• 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC
• 2008 is written as 2000=MM, 8=VIII; or MMVIII
• 1666 uses each Roman symbol in descending order: MDCLXVI

## 11l

Translation of: Python
V anums = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
V rnums = ‘M CM D CD C XC L XL X IX V IV I’.split(‘ ’)

F to_roman(=x)
V ret = ‘’
L(a, r) zip(:anums, :rnums)
(V n, x) = divmod(x, a)
ret ‘’= r * n
R ret

V test = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 40,
50, 60, 69, 70, 80, 90, 99, 100, 200, 300, 400, 500, 600, 666, 700, 800, 900, 1000,
1009, 1444, 1666, 1945, 1997, 1999, 2000, 2008, 2010, 2011, 2500, 3000, 3999]
L(val) test
print(val‘ - ’to_roman(val))

## 360 Assembly

*        Roman numerals Encode     - 11/05/2020
ROMAENC  CSECT
USING  ROMAENC,R13        base register
B      72(R15)            skip savearea
DC     17F'0'             savearea
SAVE   (14,12)            save previous context
LA     R6,1               i=1
DO  WHILE=(C,R6,LE,=A(8))       do i=1 to hbound(nums)
LR     R1,R6                i
SLA    R1,1                 ~
LH     R8,NUMS-2(R1)        n=nums(i)
MVC    PG,=CL80'.... :'     clear buffer
LA     R9,PG                @pg
XDECO  R8,XDEC              edit n
MVC    0(4,R9),XDEC+8       output n
LA     R9,7(R9)             @pg+=7
LA     R7,1                 j=1
DO  WHILE=(C,R7,LE,=A(13))        do j=1 to 13
LR     R1,R7                  j
SLA    R1,1                   ~
LH     R3,ARABIC-2(R1)        aj=arabic(j)
DO WHILE=(CR,R8,GE,R3)              while n>=aj
LR     R1,R7                    j
SLA    R1,1                     ~
LA     R4,ROMAN-2(R1)           roman(j)
MVC    0(2,R9),0(R4)            output roman(j)
IF   CLI,1(R9),NE,C' ' THEN       if roman(j)[2]=' ' then
LA     R9,2(R9)                   @pg+=2
ELSE     ,                        else
LA     R9,1(R9)                   @pg+=1
ENDIF    ,                        endif
SR     R8,R3                    n-=aj
ENDDO        ,                      endwile
LA     R7,1(R7)               j++
ENDDO        ,                    enddo j
XPRNT  PG,L'PG              print buffer
LA     R6,1(R6)             i++
ENDDO        ,                  enddo i
L      R13,4(0,R13)       restore previous savearea pointer
RETURN (14,12),RC=0       restore registers from calling save
ARABIC   DC     H'1000',H'900',H'500',H'400',H'100',H'90'
DC     H'50',H'40',H'10',H'9',H'5',H'4',H'1'
ROMAN    DC     CL2'M',CL2'CM',CL2'D',CL2'CD',CL2'C',CL2'XC'
DC     CL2'L',CL2'XL',CL2'X',CL2'IX',CL2'V',CL2'IV',CL2'I'
NUMS     DC   H'14',H'16',H'21',H'888',H'1492',H'1999',H'2020',H'3999'
PG       DS     CL80               buffer
XDEC     DS     CL12               temp for xdeco
REGEQU
END    ROMAENC
Output:
  14 : XIV
16 : XVI
21 : XXI
888 : DCCCLXXXVIII
1492 : MCDXCII
1999 : MCMXCIX
2020 : MMXX
3999 : MMMCMXCIX


## 8080 Assembly

		org	100h
jmp	test
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Takes a 16-bit integer in HL, and stores it
;; as a 0-terminated string starting at BC.
;; On exit, all registers destroyed; BC pointing at
;; end of string.
mkroman:	push	h	; put input on stack
lxi	h,mkromantab
mkromandgt:	mov	a,m	; scan ahead to next entry
ana	a
inx	h
jnz	mkromandgt
mov	a,h	; if zero, we're done
ora	l
jz	mkromandone
xthl		; load next entry from table
mov	e,m	; de = number
inx	h
mov	d,m
inx	h
xra	a	; find how many we need
subtract:	inr	a	; with trial subtraction
jc	subtract
push	psw	; keep counter
mov	a,d	; we subtracted one too many
cma		; so we need to add one back
mov	d,a
mov	a,e
cma
mov	e,a
inx	d
pop	d	; restore counter (into D)
stringouter:	dcr	d	; do we need to include one?
jz	mkromandgt
push	h	; keep string location
stringinner:	mov	a,m	; copy string into target
stax	b
ana	a	; done yet?
jz	stringdone
inx	h
inx	b	; copy next character
jmp	stringinner
stringdone:	pop	h	; restore string location
jmp	stringouter
mkromandone:	pop	d	; remove temporary variable from stack
ret
mkromantab:	db	0
db	18h,0fch,'M',0		; The value for each entry
db	7ch,0fch,'CM',0		; is stored already negated
db	0ch,0feh,'D',0		; so that it can be immediately
db	9ch,0ffh,'C',0		; This also has the convenient
db	0a6h,0ffh,'XC',0	; property of not having any
db	0ceh,0ffh,'L',0		; zero bytes except the string
db	0d8h,0ffh,'XL',0	; and row terminators.
db	0f6h,0ffh,'X',0
db	0f7h,0ffh,'IX',0
db	0fbh,0ffh,'V',0
db	0fch,0ffh,'IV',0
db	0ffh,0ffh,'I',0
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Test code
test:		mvi	c,10	; read string from console
lxi	d,dgtbufdef
call	5
lxi	h,0	; convert to integer
lxi	b,dgtbuf
ana	a
jz	convert
dad	h	; hl *= 10
mov	d,h
mov	e,l
sui	'0'
mov	e,a
mvi	d,0
inx	b
convert:	lxi	b,romanbuf	; convert to roman
call	mkroman
mvi	a,'$' ; switch string terminator stax b mvi c,9 ; output result lxi d,romanbuf jmp 5 nl: db 13,10,'$'
dgtbufdef:	db	5,0
dgtbuf:		ds	6
romanbuf:

## 8086 Assembly

### Main and Supporting Functions

The main program and test values: 70,1776,2021,3999,4000

	mov ax,0070h
call EncodeRoman
mov si,offset StringRam
call PrintString
call NewLine

mov ax,1776h
call EncodeRoman
mov si,offset StringRam
call PrintString
call NewLine

mov ax,2021h
call EncodeRoman
mov si,offset StringRam
call PrintString
call NewLine

mov ax,3999h
call EncodeRoman
mov si,offset StringRam
call PrintString
call NewLine

mov ax,4000h
call EncodeRoman
mov si,offset StringRam

ReturnToDos     ;macro that calls the int that exits dos


The EncodeRoman routine:

;ROMAN NUMERALS MODULE

EncodeRoman:
;takes a BCD value in AX and stores its Roman numeral equivalent in ram.

call UnpackBCD

cmp dh,03h
jng continue_EncodeRoman
;roman numerals only go up to 3999.
jmp errorhandler_encodeRoman_inputTooBig
continue_EncodeRoman:
mov si,offset StringRam
;using SI as destination of roman numerals.
push ax
push cx
mov ch,0
mov cl,dh					;loop counter
cmp dh,0
jz skipThousands
encodeRoman_handleThousands:
mov al,"M"
mov [ds:si],al				;store in string ram
inc si
; call PrintChar
loop encodeRoman_handleThousands
skipThousands:
pop cx
pop ax

encodeRoman_HandleHundreds:
pushall
mov bh,0
mov bl,dl  ;use bx as an offset into Roman_Lookup_Master
SHL bl,1
SHL bl,1	;multiply by 2, we are indexing into a table with 4 bytes per row.
mov di,offset Roman_Lookup_Master
mov cx,4
getChar_Hundreds:
mov al,[bx+es:di] ;get first char index
push bx
push di
mov di,offset Roman_Hund
mov bl,al
mov al,[bx+es:di]
cmp al,0
jz skipNullChar_RomanHund
mov [ds:si],al	;store in ram
inc si
; call PrintChar
skipNullChar_RomanHund:
pop di
pop bx
inc di
loop getChar_Hundreds
popall

encodeRoman_HandleTens:
pushall
mov bh,0
mov bl,ah  ;use bx as an offset into Roman_Lookup_Master
SHL bl,1
SHL bl,1	;multiply by 2, we are indexing into a table with 4 bytes per row.
mov di,offset Roman_Lookup_Master
mov cx,4
getChar_Tens:
mov al,[bx+es:di] ;get first char index
push bx
push di
mov di,offset Roman_Tens
mov bl,al
mov al,[bx+es:di]
cmp al,0
jz skipNullChar_RomanTens
mov [ds:si],al	;store in ram
inc si
; call PrintChar
skipNullChar_RomanTens:
pop di
pop bx
inc di
loop getChar_Tens
popall

encodeRoman_HandleOnes:
pushall
mov bh,0
mov bl,al  ;use bx as an offset into Roman_Lookup_Master
SHL bl,1
SHL bl,1	;multiply by 2, we are indexing into a table with 4 bytes per row.
mov di,offset Roman_Lookup_Master
mov cx,4
getChar_Ones:
mov al,[bx+es:di] ;get first char index
push bx
push di
mov di,offset Roman_Ones
mov bl,al
mov al,[bx+es:di]
cmp al,0
jz skipNullChar_RomanOnes
mov [ds:si],al	;store in ram
inc si
; call PrintChar
skipNullChar_RomanOnes:
pop di
pop bx
inc di
loop getChar_Ones
popall

mov al,0
mov [ds:si],al ;place a null terminator at the end of the string.
ret

errorhandler_encodeRoman_inputTooBig:
push ds
push ax
mov al,01h
mov byte ptr [ds:error_code],al
mov ax, offset EncodeRoman
mov word ptr [ds:error_routine],ax

mov si,offset Roman_Error
call PrintString
pop ax
pop ds
stc		;set carry, allowing program to branch if error occurred.
ret

Roman_Lookup_Master db 0,0,0,0	;0
db 0,0,0,1	;1
db 0,0,1,1	;2
db 0,1,1,1	;3
db 0,0,1,2	;4
db 0,0,0,2	;5
db 0,0,2,1	;6
db 0,2,1,1	;7
db 2,1,1,1	;8
db 0,0,1,3	;9

Roman_Ones	    db 0,"IVX"  ;the same pattern is used regardless of what power of 10 we're working with
Roman_Tens	    db 0,"XLC"
Roman_Hund	    db 0,"CDM"

UnpackBCD:
;converts a "packed" BCD value in AX to an "unpacked" value in DX.AX
;DX is the high byte, AX is the low byte.
;CLOBBERS DX AND AX.
mov dx,0
mov dl,ah
mov ah,0
push cx
mov cl,4
rol dx,cl
;BEFORE: DX = 00XYh
;AFTER:  DX = 0XY0h
ror dl,cl	;DX = 0X0Yh

rol ax,cl
;BEFORE: AX = 00XYh
;AFTER:  AX = 0XY0h
ror al,cl	;AX = 0X0Yh
pop cx
ret


Macros used:

pushall macro
push ax
push bx
push cx
push dx
push ds
push es
push di
;I forgot SI in this macro, but once you add it in the code stops working! So I left it out.
endm

popall macro
pop di
pop es
pop ds
pop dx
pop cx
pop bx
pop ax
endm


### Output

Output:
LXX
MDCCLXXVI
MMXXI
MMMCMXCIX


## Action!

DEFINE PTR="CARD"
CARD ARRAY arabic=[1000 900 500 400 100 90 50 40 10 9 5 4 1]
PTR ARRAY roman(13)

PROC InitRoman()
roman(0)="M" roman(1)="CM" roman(2)="D" roman(3)="CD"
roman(4)="C" roman(5)="XC" roman(6)="L" roman(7)="XL"
roman(8)="X" roman(9)="IX" roman(10)="V" roman(11)="IV" roman(12)="I"
RETURN

PROC EncodeRomanNumber(CARD n CHAR ARRAY res)
BYTE i,len
CHAR ARRAY tmp

res(0)=0 len=0
FOR i=0 TO 12
DO
WHILE arabic(i)<=n
DO
tmp=roman(i)
SAssign(res,tmp,len+1,len+1+tmp(0))
len==+tmp(0)
n==-arabic(i)
OD
OD
res(0)=len
RETURN

PROC Main()
CARD ARRAY data=[1990 2008 5555 1666 3888 3999]
BYTE i
CHAR ARRAY r(20)

InitRoman()
FOR i=0 TO 5
DO
EncodeRomanNumber(data(i),r)
PrintF("%U=%S%E",data(i),r)
OD
RETURN
Output:
1990=MCMXC
2008=MMVIII
5555=MMMMMDLV
1666=MDCLXVI
3888=MMMDCCCLXXXVIII
3999=MMMCMXCIX


## ActionScript

function arabic2roman(num:Number):String {
var lookup:Object = {M:1000, CM:900, D:500, CD:400, C:100, XC:90, L:50, XL:40, X:10, IX:9, V:5, IV:4, I:1};
var roman:String = "", i:String;
for (i in lookup) {
while (num >= lookup[i]) {
roman += i;
num -= lookup[i];
}
}
return roman;
}
trace("1990 in roman is " + arabic2roman(1990));
trace("2008 in roman is " + arabic2roman(2008));
trace("1666 in roman is " + arabic2roman(1666));

Output:
1990 in roman is MCMXC
2008 in roman is MMVIII
1666 in roman is MDCLXVI


And the reverse:

function roman2arabic(roman:String):Number {
var romanArr:Array = roman.toUpperCase().split('');
var lookup:Object = {I:1, V:5, X:10, L:50, C:100, D:500, M:1000};
var num:Number = 0, val:Number = 0;
while (romanArr.length) {
val = lookup[romanArr.shift()];
num += val * (val < lookup[romanArr[0]] ? -1 : 1);
}
return num;
}
trace("MCMXC in arabic is " + roman2arabic("MCMXC"));
trace("MMVIII in arabic is " + roman2arabic("MMVIII"));
trace("MDCLXVI in arabic is " + roman2arabic("MDCLXVI"));

Output:
MCMXC in arabic is 1990
MMVIII in arabic is 2008
MDCLXVI in arabic is 1666

with Ada.Text_IO;  use Ada.Text_IO;

procedure Roman_Numeral_Test is
function To_Roman (Number : Positive) return String is
subtype Digit is Integer range 0..9;
function Roman (Figure : Digit; I, V, X : Character) return String is
begin
case Figure is
when 0 => return "";
when 1 => return "" & I;
when 2 => return I & I;
when 3 => return I & I & I;
when 4 => return I & V;
when 5 => return "" & V;
when 6 => return V & I;
when 7 => return V & I & I;
when 8 => return V & I & I & I;
when 9 => return I & X;
end case;
end Roman;
begin
pragma Assert (Number >= 1 and Number < 4000);
return
Roman (Number / 1000,       'M', ' ', ' ') &
Roman (Number / 100 mod 10, 'C', 'D', 'M') &
Roman (Number / 10 mod 10,  'X', 'L', 'C') &
Roman (Number mod 10,       'I', 'V', 'X');
end To_Roman;
begin
Put_Line (To_Roman (1999));
Put_Line (To_Roman (25));
Put_Line (To_Roman (944));
end Roman_Numeral_Test;

Output:
 MCMXCIX
XXV
CMXLIV


## ALGOL 68

Works with: ALGOL 68 version Revision 1 - no extensions to language used
Works with: ALGOL 68G version Any - tested with release 1.18.0-9h.tiny
Works with: ELLA ALGOL 68 version Any (with appropriate job cards) - tested with release 1.8-8d
[]CHAR roman =        "MDCLXVmdclxvi"; # UPPERCASE for thousands #
[]INT arabic =       (1000000, 500000, 100000, 50000, 10000, 5000, 1000, 500, 100, 50, 10, 5, 1);
[]INT adjust arabic = (100000, 100000,  10000, 10000,  1000, 1000,  100, 100,  10, 10,  1, 1, 0);

PROC arabic to roman = (INT dclxvi)STRING: (
INT in := dclxvi; # 666 #
STRING out := "";
FOR scale TO UPB roman WHILE in /= 0 DO
INT multiples = in OVER arabic[scale];
in -:= arabic[scale] * multiples;
out +:= roman[scale] * multiples;
IF in >= -adjust arabic[scale] + arabic[scale] THEN
in -:= -adjust arabic[scale] + arabic[scale];
out +:=  adjust roman[scale] +  roman[scale]
FI
OD;
out
);

main:(
[]INT test = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,25,30,40,50,60,69,70,
80,90,99,100,200,300,400,500,600,666,700,800,900,1000,1009,1444,1666,1945,1997,1999,
2000,2008,2500,3000,4000,4999,5000,6666,10000,50000,100000,500000,1000000,max int);
FOR key TO UPB test DO
INT val = test[key];
print((val, " - ", arabic to roman(val), new line))
OD
)
Output:

(last example is manually wrapped)

         +1 - i
+2 - ii
+3 - iii
+4 - iv
+5 - v
+6 - vi
+7 - vii
+8 - viii
+9 - ix
+10 - x
+11 - xi
+12 - xii
+13 - xiii
+14 - xiv
+15 - xv
+16 - xvi
+17 - xvii
+18 - xviii
+19 - xix
+20 - xx
+25 - xxv
+30 - xxx
+40 - xl
+50 - l
+60 - lx
+69 - lxix
+70 - lxx
+80 - lxxx
+90 - xc
+99 - xcix
+100 - c
+200 - cc
+300 - ccc
+400 - cd
+500 - d
+600 - dc
+666 - dclxvi
+700 - dcc
+800 - dccc
+900 - cm
+1000 - m
+1009 - mix
+1444 - mcdxliv
+1666 - mdclxvi
+1945 - mcmxlv
+1997 - mcmxcvii
+1999 - mcmxcix
+2000 - mm
+2008 - mmviii
+2500 - mmd
+3000 - mmm
+4000 - mV
+4999 - mVcmxcix
+5000 - V
+6666 - Vmdclxvi
+10000 - X
+50000 - L
+100000 - C
+500000 - D
+1000000 - M
+2147483647 - MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCDLXXXmmmdcxlvii

## ALGOL W

Works with: awtoc version any - tested with release Mon Apr 27 14:25:27 NZST 2009
BEGIN

PROCEDURE ROMAN (INTEGER VALUE NUMBER; STRING(15) RESULT CHARACTERS; INTEGER RESULT LENGTH);
COMMENT
Returns the Roman number of an integer between 1 and 3999.
"MMMDCCCLXXXVIII" (15 characters long) is the longest Roman number under 4000;
BEGIN
INTEGER PLACE, POWER;

PROCEDURE APPEND (STRING(1) VALUE C);
BEGIN CHARACTERS(LENGTH|1) := C; LENGTH := LENGTH + 1 END;

PROCEDURE I; APPEND(CASE PLACE OF ("I","X","C","M"));
PROCEDURE V; APPEND(CASE PLACE OF ("V","L","D"));
PROCEDURE X; APPEND(CASE PLACE OF ("X","C","M"));

ASSERT (NUMBER >= 1) AND (NUMBER < 4000);

CHARACTERS := "               ";
LENGTH := 0;
POWER := 1000;
PLACE := 4;
WHILE PLACE > 0 DO
BEGIN
CASE NUMBER DIV POWER + 1 OF BEGIN
BEGIN            END;
BEGIN I          END;
BEGIN I; I       END;
BEGIN I; I; I    END;
BEGIN I; V       END;
BEGIN V          END;
BEGIN V; I       END;
BEGIN V; I; I    END;
BEGIN V; I; I; I END;
BEGIN I; X       END
END;
NUMBER := NUMBER REM POWER;
POWER := POWER DIV 10;
PLACE := PLACE - 1
END
END ROMAN;

INTEGER I;
STRING(15) S;

ROMAN(1, S, I);    WRITE(S, I);
ROMAN(3999, S, I); WRITE(S, I);
ROMAN(3888, S, I); WRITE(S, I);
ROMAN(2009, S, I); WRITE(S, I);
ROMAN(405, S, I);  WRITE(S, I);
END.
Output:
I                           1
MMMCMXCIX                   9
MMMDCCCLXXXVIII            15
MMIX                        4
CDV                         3


## APL

Works with: Dyalog APL
toRoman←{
⍝ Digits and corresponding values
ds←((⊢≠⊃)⊆⊢)' M CM D CD C XC L XL X IX V IV I'
vs←1000, ,100 10 1∘.×9 5 4 1
⍝ Input ≤ 0 is invalid
⍵≤0:⎕SIGNAL 11
{   0=d←⊃⍸vs≤⍵:⍬    ⍝ Find highest digit in number
(d⊃ds),∇⍵-d⊃vs  ⍝ While one exists, add it and subtract from number
}⍵
}

Output:
      toRoman¨ 1990 2008 1666 2021
MCMXC  MMVIII  MDCLXVI  MMXXI 

## AppleScript

Translation of: JavaScript

(ES6 version)

(mapAccumL version)

------------------ ROMAN INTEGER STRINGS -----------------

-- roman :: Int -> String
on roman(n)
set kvs to {["M", 1000], ["CM", 900], ["D", 500], ¬
["CD", 400], ["C", 100], ["XC", 90], ["L", 50], ¬
["XL", 40], ["X", 10], ["IX", 9], ["V", 5], ¬
["IV", 4], ["I", 1]}

on |λ|(balance, kv)
set {k, v} to kv
set {q, r} to quotRem(balance, v)
if q > 0 then
{r, concat(replicate(q, k))}
else
{r, ""}
end if
end |λ|
end script

end roman

--------------------------- TEST -------------------------
on run

map(roman, [2016, 1990, 2008, 2000, 1666])

--> {"MMXVI", "MCMXC", "MMVIII", "MM", "MDCLXVI"}
end run

---------------- GENERIC LIBRARY FUNCTIONS ---------------

-- concat :: [[a]] -> [a] | [String] -> String
on concat(xs)
script append
on |λ|(a, b)
a & b
end |λ|
end script

if length of xs > 0 and ¬
class of (item 1 of xs) is string then
set unit to ""
else
set unit to {}
end if
foldl(append, unit, xs)
end concat

-- foldl :: (a -> b -> a) -> a -> [b] -> a
on foldl(f, startValue, xs)
tell mReturn(f)
set v to startValue
set lng to length of xs
repeat with i from 1 to lng
set v to |λ|(v, item i of xs, i, xs)
end repeat
return v
end tell
end foldl

-- map :: (a -> b) -> [a] -> [b]
on map(f, xs)
tell mReturn(f)
set lng to length of xs
set lst to {}
repeat with i from 1 to lng
set end of lst to |λ|(item i of xs, i, xs)
end repeat
return lst
end tell
end map

-- 'The mapAccumL function behaves like a combination of map and foldl;
-- it applies a function to each element of a list, passing an
-- accumulating parameter from left to right, and returning a final
-- value of this accumulator together with the new list.' (see Hoogle)

-- mapAccumL :: (acc -> x -> (acc, y)) -> acc -> [x] -> (acc, [y])
on mapAccumL(f, acc, xs)
script
on |λ|(a, x)
tell mReturn(f) to set pair to |λ|(item 1 of a, x)
[item 1 of pair, (item 2 of a) & {item 2 of pair}]
end |λ|
end script

foldl(result, [acc, {}], xs)
end mapAccumL

-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: Handler -> Script
on mReturn(f)
if class of f is script then
f
else
script
property |λ| : f
end script
end if
end mReturn

--  quotRem :: Integral a => a -> a -> (a, a)
on quotRem(m, n)
{m div n, m mod n}
end quotRem

-- Egyptian multiplication - progressively doubling a list, appending
-- stages of doubling to an accumulator where needed for binary
-- assembly of a target length

-- replicate :: Int -> a -> [a]
on replicate(n, a)
set out to {}
if n < 1 then return out
set dbl to {a}

repeat while (n > 1)
if (n mod 2) > 0 then set out to out & dbl
set n to (n div 2)
set dbl to (dbl & dbl)
end repeat
return out & dbl
end replicate

-- snd :: (a, b) -> b
on snd(xs)
if class of xs is list and length of xs = 2 then
item 2 of xs
else
missing value
end if
end snd

Output:
{"MMXVI", "MCMXC", "MMVIII", "MM", "MDCLXVI"}

## Arturo

Translation of: Nim
nums: [[1000 "M"] [900 "CM"] [500 "D"] [400 "CD"] [100 "C"] [90 "XC"]
[50 "L"] [40 "XL"] [10 "X"] [9 "IX"] [5 "V"] [4 "IV"] [1 "I"])

toRoman: function [x][
ret: ""
idx: 0
initial: x
loop nums 'num [
d: num\0
l: num\1

i: 0
while [i<initial/d] [
ret: ret ++ l
i: i+1
]

initial: mod initial d
]
return ret
]

loop [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 25 30 40
50 60 69 70 80 90 99 100 200 300 400 500 600 666 700 800 900
1000 1009 1444 1666 1945 1997 1999 2000 2008 2010 2011 2500
3000 3999] 'n
-> print [n "->" toRoman n]

Output:
1 -> I
2 -> II
3 -> III
4 -> IV
5 -> V
6 -> VI
7 -> VII
8 -> VIII
9 -> IX
10 -> X
11 -> XI
12 -> XII
13 -> XIII
14 -> XIV
15 -> XV
16 -> XVI
17 -> XVII
18 -> XVIII
19 -> XIX
20 -> XX
25 -> XXV
30 -> XXX
40 -> XL
50 -> L
60 -> LX
69 -> LXIX
70 -> LXX
80 -> LXXX
90 -> XC
99 -> XCIX
100 -> C
200 -> CC
300 -> CCC
400 -> CD
500 -> D
600 -> DC
666 -> DCLXVI
700 -> DCC
800 -> DCCC
900 -> CM
1000 -> M
1009 -> MIX
1444 -> MCDXLIV
1666 -> MDCLXVI
1945 -> MCMXLV
1997 -> MCMXCVII
1999 -> MCMXCIX
2000 -> MM
2008 -> MMVIII
2010 -> MMX
2011 -> MMXI
2500 -> MMD
3000 -> MMM
3999 -> MMMCMXCIX

## AutoHotkey

Translation of: C++
MsgBox % stor(444)

stor(value)
{
romans = M,CM,D,CD,C,XC,L,XL,X,IX,V,IV,I
M := 1000
CM := 900
D := 500
CD := 400
C := 100
XC := 90
L := 50
XL := 40
X := 10
IX := 9
V := 5
IV := 4
I := 1
Loop, Parse, romans, ,
{
While, value >= %A_LoopField%
{
result .= A_LoopField
value := value - (%A_LoopField%)
}
}
Return result . "O"
}


## Autolisp

(defun c:roman() (romanNumber (getint "\n Enter number > "))
(defun romanNumber (n / uni dec hun tho nstr strlist nlist rom)
(if (and (> n 0) (<= n 3999))
(progn
(setq
UNI (list "" "I" "II" "III" "IV" "V" "VI" "VII" "VIII" "IX")
DEC (list "" "X" "XX" "XXX" "XL" "L" "LX" "LXX" "LXXX" "XC")
HUN (list "" "C" "CC" "CCC" "CD" "D" "DC" "DCC" "DCCC" "CM")
THO (list "" "M" "MM" "MMM")
nstr (itoa n)
)
(while (> (strlen nstr) 0) (setq strlist (append strlist (list (substr nstr 1 1))) nstr (substr nstr 2 (strlen nstr))))
(setq nlist (mapcar 'atoi strlist))
(cond
((> n 999)(setq rom(strcat(nth (car nlist) THO)(nth (cadr nlist) HUN)(nth (caddr nlist) DEC) (nth (last nlist)UNI ))))
((and (> n 99)(<= n 999))(setq rom(strcat (nth (car nlist) HUN)(nth (cadr nlist) DEC) (nth (last nlist)UNI ))))
((and (> n 9)(<= n 99))(setq rom(strcat (nth (car nlist) DEC) (nth (last nlist)UNI ))))
((<= n 9)(setq rom(nth (last nlist)UNI)))
)
)
(princ "\nNumber out of range!")
)
rom
)
Output:
1577 "MDLXXVII"
3999 "MMMCMXCIX"
888 "DCCCLXXXVIII"
159 "CLIX"


## AWK

# syntax: GAWK -f ROMAN_NUMERALS_ENCODE.AWK
BEGIN {
leng = split("1990 2008 1666",arr," ")
for (i=1; i<=leng; i++) {
n = arr[i]
printf("%s = %s\n",n,dec2roman(n))
}
exit(0)
}
function dec2roman(number,  v,w,x,y,roman1,roman10,roman100,roman1000) {
number = int(number) # force to integer
if (number < 1 || number > 3999) { # number is too small | big
return
}
split("I II III IV V VI VII VIII IX",roman1," ")   # 1 2 ... 9
split("X XX XXX XL L LX LXX LXXX XC",roman10," ")  # 10 20 ... 90
split("C CC CCC CD D DC DCC DCCC CM",roman100," ") # 100 200 ... 900
split("M MM MMM",roman1000," ")                    # 1000 2000 3000
v = (number - (number % 1000)) / 1000
number = number % 1000
w = (number - (number % 100)) / 100
number = number % 100
x = (number - (number % 10)) / 10
y = number % 10
return(roman1000[v] roman100[w] roman10[x] roman1[y])
}

Output:
1990 = MCMXC
2008 = MMVIII
1666 = MDCLXVI


## BASIC

### Applesoft BASIC

 1 N = 1990: GOSUB 5: PRINT N" = "V$2 N = 2008: GOSUB 5: PRINT N" = "V$
3 N = 1666: GOSUB 5: PRINT N" = "V$; 4 END 5 V = N:V$ = "": FOR I = 0 TO 12: FOR L = 1 TO 0 STEP 0:A =  VAL ( MID$("1E3900500400100+90+50+40+10+09+05+04+01",I * 3 + 1,3)) 6 L = (V - A) > = 0:V$ = V$+ MID$ ("M.CMD.CDC.XCL.XLX.IXV.IVI",I * 2 + 1,(I -  INT (I / 2) * 2 + 1) * L):V = V - A * L: NEXT L,I
7  RETURN


### ASIC

Translation of: DWScript
REM Roman numerals/Encode
DIM Weights(12)
DIM Symbols$(12) DATA 1000, "M", 900, "CM", 500, "D", 400, "CD", 100, "C", 90, "XC", 50, "L" DATA 40, "XL", 10, "X", 9, "IX", 5, "V", 4, "IV", 1, "I" REM 3888 or MMMDCCCLXXXVIII (15 chars) is the longest string properly encoded REM with these symbols. FOR J = 0 TO 12 READ Weights(J) READ Symbols$(J)
NEXT J

AValue = 1990
GOSUB ToRoman:
PRINT Roman$REM MCMXC AValue = 2022 GOSUB ToRoman: PRINT Roman$
REM MMXXII
AValue = 3888
GOSUB ToRoman:
PRINT Roman$REM MMMDCCCLXXXVIII END ToRoman: REM Result: Roman$
Roman$= "" I = 0 Loop: IF (I > 12 THEN ExitToRoman: IF AValue <= 0 THEN ExitToRoman: WHILE AValue >= Weights(I) Roman$ = Roman$+ Symbols$(I)
AValue = AValue - Weights(I)
WEND
I = I + 1
GOTO Loop:
ExitToRoman:
RETURN


### BaCon

OPTION BASE 1

GLOBAL roman$[] = { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" } GLOBAL number[] = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 } FUNCTION toroman$(value)

LOCAL result$DOTIMES UBOUND(number) WHILE value >= number[_] result$ = result$& roman$[_]
DECR value, number[_]
WEND
DONE

RETURN result$ENDFUNC PRINT toroman$(1990)
PRINT toroman$(2008) PRINT toroman$(1666)
Output:
MCMXC
MMVIII
MDCLXVI


### BASIC256

Works with: BASIC256

print 1666+" = "+convert$(1666) print 2008+" = "+convert$(2008)
print 1001+" = "+convert$(1001) print 1999+" = "+convert$(1999)

function convert$(value) convert$=""
arabic = {1000, 900, 500, 400, 100, 90, 50,  40,  10,  9,  5,   4,  1 }
roman$= {"M", "CM", "D","CD", "C","XC","L","XL","X","IX","V","IV","I"} for i = 0 to 12 while value >= arabic[i] convert$ += roman$[i] value = value - arabic[i] end while next i end function Output: 1666 = MDCLXVI 2008 = MMVIII 1001 = MI 1999 = MCMXCIX  ### BBC BASIC  PRINT ;1999, FNroman(1999) PRINT ;2012, FNroman(2012) PRINT ;1666, FNroman(1666) PRINT ;3888, FNroman(3888) END DEF FNroman(n%) LOCAL i%, r$, arabic%(), roman$() DIM arabic%(12), roman$(12)
arabic%() = 1,   4,   5,   9,  10,  40,  50,  90, 100, 400, 500, 900,1000
roman$() = "I","IV", "V","IX", "X","XL", "L","XC", "C","CD", "D","CM", "M" FOR i% = 12 TO 0 STEP -1 WHILE n% >= arabic%(i%) r$ += roman$(i%) n% -= arabic%(i%) ENDWHILE NEXT = r$

Output:
1999      MCMXCIX
2012      MMXII
1666      MDCLXVI
3888      MMMDCCCLXXXVIII


### Chipmunk Basic

Works with: Chipmunk Basic version 3.6.4
Translation of: GW-BASIC
100 cls
110 dim arabic(12), roman$(12) 120 for j = 0 to 12 : read arabic(j),roman$(j) : next j
130 data 1000,"M", 900,"CM", 500,"D", 400,"CD", 100,"C", 90,"XC"
140 data 50,"L",40,"XL",10,"X",9,"IX",5,"V",4,"IV",1,"I"
187 avalor = 1990 : print avalor "= "; : gosub 220 : print roman$' MCMXC 188 avalor = 2008 : print avalor "= "; : gosub 220 : print roman$ ' MMXXII
189 avalor = 1666 : print avalor "= "; : gosub 220 : print roman$' MDCLXVI 200 end 210 rem Encode to Roman 220 roman$ = "" : i = 0
230 while (i <= 12) and (avalor > 0)
240  while avalor >= arabic(i)
250   roman$= roman$+roman$(i) 260 avalor = avalor-arabic(i) 270 wend 280 i = i+1 290 wend 300 return  Output: 1990 = MCMXC 2008 = MMVIII 1666 = MDCLXVI ### Commodore BASIC Works with: Commodore BASIC version 7.0 C-128 version: 100 DIM RN$(12),NV(12)
110 FOR I=0 TO 12
120 : READ RN$(I), NV(I) 130 NEXT I 140 DATA M,1000, CM,900, D,500, CD,400 150 DATA C, 100, XC, 90, L, 50, XL, 40 160 DATA X, 10, IX, 9, V, 5, IV, 4 170 DATA I, 1 180 PRINT CHR$(19);CHR$(19);CHR$(147);CHR$(18); 190 PRINT "***** ROMAN NUMERAL ENCODER *****";CHR$(27);"T"
200 DO
210 : PRINT "ENTER NUMBER (0 TO QUIT):";
220 : OPEN 1,0:INPUT#1,AN$:CLOSE 1:PRINT 230 : AN=VAL(AN$):IF AN=0 THEN EXIT
240 : RN$="" 250 : DO WHILE AN > 0 260 : FOR I=0 TO 12 270 : IF AN >= NV(I) THEN BEGIN 280 : RN$ = RN$+ RN$(I)
290 :       AN = AN - NV(I)
300 :       GOTO 330
310 :     BEND
320 :   NEXT I
330 : LOOP
340 : PRINT RN$;CHR$(13)
350 LOOP

Works with: Commodore BASIC version 3.5

C-16/116/Plus-4 version (BASIC 3.5 has DO/LOOP but not BEGIN/BEND)

100 DIM RN$(12),NV(12) 110 FOR I=0 TO 12 120 : READ RN$(I), NV(I)
130 NEXT I
140 DATA M,1000, CM,900, D,500, CD,400
150 DATA C, 100, XC, 90, L, 50, XL, 40
160 DATA X,  10, IX,  9, V,  5, IV,  4
170 DATA I,   1
180 PRINT CHR$(19);CHR$(19);CHR$(147);CHR$(18);
190 PRINT "*****    ROMAN NUMERAL ENCODER     *****";CHR$(27);"T" 200 DO 210 : PRINT "ENTER NUMBER (0 TO QUIT):"; 220 : OPEN 1,0:INPUT#1,AN$:CLOSE 1:PRINT
230 : AN=VAL(AN$):IF AN=0 THEN EXIT 240 : RN$=""
250 : DO WHILE AN > 0
260 :   FOR I=0 TO 12
270 :     IF AN < NV(I) THEN 320
280 :     RN$= RN$+ RN$(I) 290 : AN = AN - NV(I) 300 : I = 12 320 : NEXT I 330 : LOOP 340 : PRINT RN$;CHR$(13) 350 LOOP  Works with: Commodore BASIC version 2.0 This version works on any Commodore, though the title banner should be adjusted to match the color and screen width of the particular machine. 100 DIM RN$(12),NV(12)
110 FOR I=0 TO 12
120 : READ RN$(I), NV(I) 130 NEXT I 140 DATA M,1000, CM,900, D,500, CD,400 150 DATA C, 100, XC, 90, L, 50, XL, 40 160 DATA X, 10, IX, 9, V, 5, IV, 4 170 DATA I, 1 180 PRINT CHR$(19);CHR$(19);CHR$(147);CHR$(18); 190 PRINT "***** ROMAN NUMERAL ENCODER *****"; 200 REM BEGIN MAIN LOOP 210 : PRINT "NUMBER (0 TO QUIT):"; 220 : OPEN 1,0:INPUT#1,AN$:CLOSE 1:PRINT
230 : AN=VAL(AN$):IF AN=0 THEN END 240 : RN$=""
250 : IF AN <= 0 THEN 340
260 :   FOR I=0 TO 12
270 :     IF AN < NV(I) THEN 320
280 :     RN$= RN$+ RN$(I) 290 : AN = AN - NV(I) 300 : I = 12 320 : NEXT I 330 : GOTO 250 340 : PRINT RN$;CHR$(13) 350 GOTO 210  The output is the same for all the above versions: Output: ***** ROMAN NUMERAL ENCODER ***** ENTER NUMBER (0 TO QUIT):2009 MMIX ENTER NUMBER (0 TO QUIT):1666 MDCLXVI ENTER NUMBER (0 TO QUIT):3888 MMMDCCCLXXXVIII ENTER NUMBER (0 TO QUIT):0 READY. ### FreeBASIC Works with: FreeBASIC DIM SHARED arabic(0 TO 12) AS Integer => {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 } DIM SHARED roman(0 TO 12) AS String*2 => {"M", "CM", "D","CD", "C","XC","L","XL","X","IX","V","IV","I"} FUNCTION toRoman(value AS Integer) AS String DIM i AS Integer DIM result AS String FOR i = 0 TO 12 DO WHILE value >= arabic(i) result = result + roman(i) value = value - arabic(i) LOOP NEXT i toRoman = result END FUNCTION 'Testing PRINT "2009 = "; toRoman(2009) PRINT "1666 = "; toRoman(1666) PRINT "3888 = "; toRoman(3888)  Output:  2009 = MMIX 1666 = MDCLXVI 3888 = MMMDCCCLXXXVIII  Another solution: ' FB 1.05.0 Win64 Function romanEncode(n As Integer) As String If n < 1 OrElse n > 3999 Then Return "" '' can only encode numbers in range 1 to 3999 Dim roman1(0 To 2) As String = {"MMM", "MM", "M"} Dim roman2(0 To 8) As String = {"CM", "DCCC", "DCC", "DC", "D", "CD", "CCC", "CC", "C"} Dim roman3(0 To 8) As String = {"XC", "LXXX", "LXX", "LX", "L", "XL", "XXX", "XX", "X"} Dim roman4(0 To 8) As String = {"IX", "VIII", "VII", "VI", "V", "IV", "III", "II", "I"} Dim As Integer thousands, hundreds, tens, units thousands = n \ 1000 n Mod= 1000 hundreds = n \ 100 n Mod= 100 tens = n \ 10 units = n Mod 10 Dim roman As String = "" If thousands > 0 Then roman += roman1(3 - thousands) If hundreds > 0 Then roman += roman2(9 - hundreds) If tens > 0 Then roman += roman3(9 - tens) If units > 0 Then roman += roman4(9 - units) Return roman End Function Dim a(2) As Integer = {1990, 2008, 1666} For i As Integer = 0 To 2 Print a(i); " => "; romanEncode(a(i)) Next Print Print "Press any key to quit" Sleep  Output:  1990 => MCMXC 2008 => MMVIII 1666 => MDCLXVI  ### FutureBasic window 1 local fn DecimaltoRoman( decimal as short ) as Str15 short arabic(12) Str15 roman(12) long i Str15 result : result = "" arabic(0) = 1000 : arabic(1) = 900 : arabic(2) = 500 : arabic(3) = 400 arabic(4) = 100 : arabic(5) = 90 : arabic(6) = 50 : arabic(7) = 40 arabic(8) = 10 : arabic(9) = 9 : arabic(10) = 5 : arabic(11) = 4: arabic(12) = 1 roman(0) = "M" : roman(1) = "CM" : roman(2) = "D" : roman(3) = "CD" roman(4) = "C" : roman(5) = "XC" : roman(6) = "L" : roman(7) = "XL" roman(8) = "X" : roman(9) = "IX" : roman(10) = "V" : roman(11) = "IV" : roman(12) = "I" for i = 0 to 12 while ( decimal >= arabic(i) ) result = result + roman(i) decimal = decimal - arabic(i) wend next i if result == "" then result = "Zepherium" end fn = result print "1990 = "; fn DecimaltoRoman( 1990 ) print "2008 = "; fn DecimaltoRoman( 2008 ) print "2016 = "; fn DecimaltoRoman( 2016 ) print "1666 = "; fn DecimaltoRoman( 1666 ) print "3888 = "; fn DecimaltoRoman( 3888 ) print "1914 = "; fn DecimaltoRoman( 1914 ) print "1000 = "; fn DecimaltoRoman( 1000 ) print " 513 = "; fn DecimaltoRoman( 513 ) print " 33 = "; fn DecimaltoRoman( 33 ) HandleEvents Output: 1990 = MCMXC 2008 = MMVIII 2016 = MMXVI 1666 = MDCLXVI 3888 = MMMDCCCLXXXVIII 1914 = MCMXIV 1000 = M 513 = DXIII 33 = XXXIII  ### Gambas Translation of: FreeBASIC Public Sub Main() 'Testing Print "2009 = "; toRoman(2009) Print "1666 = "; toRoman(1666) Print "3888 = "; toRoman(3888) End Function toRoman(value As Integer) As String Dim result As String Dim arabic As Integer[] = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1] Dim roman As String[] = ["M", "CM", "D", "CD", "C", "XC", "L" , "XL", "X", "IX", "V", "IV", "I"] For i As Integer = 0 To arabic.Max Do While value >= arabic[i] result &= roman[i] value -= arabic[i] Loop Next Return result End Function  Output: Same as FreeBASIC entry. ### GW-BASIC Translation of: DWScript Works with: BASICA  10 REM Roman numerals/Encode 20 DIM WEIGHTS%(12), SYMBOLS$(12)
30 FOR J% = 0 TO 12: READ WEIGHTS%(J%), SYMBOLS$(J%): NEXT J% 40 DATA 1000, "M", 900, "CM", 500, "D", 400, "CD", 100, "C", 90, "XC" 50 DATA 50, "L", 40, "XL", 10, "X", 9, "IX", 5, "V", 4, "IV", 1, "I" 60 REM 3888 or MMMDCCCLXXXVIII (15 chars) is 70 REM the longest string properly encoded 80 REM with these symbols. 90 AVALUE% = 1990: GOSUB 1000: PRINT ROMAN$ ' MCMXC
100 AVALUE% = 2022: GOSUB 1000: PRINT ROMAN$' MMXXII 110 AVALUE% = 3888: GOSUB 1000: PRINT ROMAN$ ' MMMDCCCLXXXVIII
120 END
990 REM Encode to roman
1000 ROMAN$= "": I% = 0 1010 WHILE (I% <= 12) AND (AVALUE% > 0) 1020 WHILE AVALUE% >= WEIGHTS%(I%) 1030 ROMAN$ = ROMAN$+ SYMBOLS$(I%)
1040   AVALUE% = AVALUE% - WEIGHTS%(I%)
1050  WEND
1060  I% = I% + 1
1070 WEND
1080 RETURN

Output:
MCMXC
MMXXII
MMMDCCCLXXXVIII


### IS-BASIC

100 PROGRAM "Roman.bas"
110 DO
120   PRINT :INPUT PROMPT "Enter an arabic number: ":N
130   IF N<1 THEN EXIT DO
140   PRINT TOROMAN$(N) 150 LOOP 160 DEF TOROMAN$(X)
170   IF X>3999 THEN
180     LET TOROMAN$="Too big." 190 EXIT DEF 200 END IF 210 RESTORE 220 LET SUM$=""
230   FOR I=1 TO 13
240     READ ARABIC,ROMAN$250 DO WHILE X>=ARABIC 260 LET SUM$=SUM$&ROMAN$
270       LET X=X-ARABIC
280     LOOP
290   NEXT
300   LET TOROMAN$=SUM$
310 END DEF
320 DATA 1000,"M",900,"CM",500,"D",400,"CD",100,"C",90,"XC"
330 DATA 50,"L",40,"XL",10,"X",9,"IX",5,"V",4,"IV",1,"I"

### Liberty BASIC

Works with: Just BASIC
    dim arabic( 12)
for i =0 to 12
arabic( i) =k
next i
data 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1

dim roman$( 12) for i =0 to 12 read k$
roman$( i) =k$
next i
data "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"

print 2009, toRoman$( 2009) print 1666, toRoman$( 1666)
print 3888, toRoman$( 3888) end function toRoman$( value)
i       =0
result$="" for i = 0 to 12 while value >=arabic( i) result$ = result$+ roman$( i)
value   = value   - arabic( i)
wend
next i
toRoman$=result$
end function
2009          MMIX
1666          MDCLXVI
3888          MMMDCCCLXXXVIII


### Microsoft Small Basic

Translation of: DWScript
arabicNumeral = 1990
ConvertToRoman()
TextWindow.WriteLine(romanNumeral) 'MCMXC
arabicNumeral = 2018
ConvertToRoman()
TextWindow.WriteLine(romanNumeral) 'MMXVIII
arabicNumeral = 3888
ConvertToRoman()
TextWindow.WriteLine(romanNumeral) 'MMMDCCCLXXXVIII

Sub ConvertToRoman
weights[0] = 1000
weights[1] =  900
weights[2] =  500
weights[3] =  400
weights[4] =  100
weights[5] =   90
weights[6] =   50
weights[7] =   40
weights[8] =   10
weights[9] =    9
weights[10] =   5
weights[11] =   4
weights[12] =   1
symbols[0] = "M"
symbols[1] = "CM"
symbols[2] = "D"
symbols[3] = "CD"
symbols[4] = "C"
symbols[5] = "XC"
symbols[6] = "L"
symbols[7] = "XL"
symbols[8] = "X"
symbols[9] = "IX"
symbols[10] = "V"
symbols[11] = "IV"
symbols[12] = "I"
romanNumeral = ""
i = 0
While (i <= 12) And (arabicNumeral > 0)
While arabicNumeral >= weights[i]
romanNumeral = Text.Append(romanNumeral, symbols[i])
arabicNumeral = arabicNumeral - weights[i]
EndWhile
i = i + 1
EndWhile
EndSub
Output:
MCMXC
MMXVIII
MMMDCCCLXXXVIII


### Nascom BASIC

Translation of: DWScript
Works with: Nascom ROM BASIC version 4.7
10 REM Roman numerals/Encode
20 DIM WEIGHTS(12),SYMBOLS$(12) 30 FOR I=0 TO 12 40 READ WEIGHTS(I),SYMBOLS$(I)
50 NEXT I
60 DATA 1000,M,900,CM,500,D,400,CD,100,C,90,XC
70 DATA 50,L,40,XL,10,X,9,IX,5,V,4,IV,1,I
80 REM ** 3888 or MMMDCCCLXXXVIII (15 chars) is
90 REM    the longest string properly encoded
100 REM   with these symbols.
110 V=1990:GOSUB 500
120 PRINT ROMAN$:REM MCMXC 130 V=2022:GOSUB 500 140 PRINT ROMAN$:REM MMXXII
150 V=3888:GOSUB 500
160 PRINT ROMAN$:REM MMMDCCCLXXXVIII 170 END 490 REM ** Encode to roman 500 ROMAN$=""
510 I=0
520 IF I>12 OR V<=0 THEN RETURN
530 IF V<WEIGHTS(I) THEN 570
540 ROMAN$=ROMAN$+SYMBOLS$(I) 550 V=V-WEIGHTS(I) 560 GOTO 530 570 I=I+1 580 GOTO 520 590 RETURN  Output: MCMXC MMXXII MMMDCCCLXXXVIII  ### PowerBASIC Translation of: BASIC Works with: PB/Win version 8+ Works with: PB/CC version 5 FUNCTION toRoman(value AS INTEGER) AS STRING DIM arabic(0 TO 12) AS INTEGER DIM roman(0 TO 12) AS STRING ARRAY ASSIGN arabic() = 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 ARRAY ASSIGN roman() = "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" DIM i AS INTEGER DIM result AS STRING FOR i = 0 TO 12 DO WHILE value >= arabic(i) result = result & roman(i) value = value - arabic(i) LOOP NEXT i toRoman = result END FUNCTION FUNCTION PBMAIN 'Testing ? "2009 = " & toRoman(2009) ? "1666 = " & toRoman(1666) ? "3888 = " & toRoman(3888) END FUNCTION ### PureBasic #SymbolCount = 12 ;0 based count DataSection denominations: Data.s "M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I" ;0-12 denomValues: Data.i 1000,900,500,400,100,90,50,40,10,9,5,4,1 ;values in decending sequential order EndDataSection ;-setup Structure romanNumeral symbol.s value.i EndStructure Global Dim refRomanNum.romanNumeral(#SymbolCount) Restore denominations For i = 0 To #SymbolCount Read.s refRomanNum(i)\symbol Next Restore denomValues For i = 0 To #SymbolCount Read refRomanNum(i)\value Next Procedure.s decRoman(n) ;converts a decimal number to a roman numeral Protected roman$, i

For i = 0 To #SymbolCount
Repeat
If n >= refRomanNum(i)\value
roman$+ refRomanNum(i)\symbol n - refRomanNum(i)\value Else Break EndIf ForEver Next ProcedureReturn roman$
EndProcedure

If OpenConsole()

PrintN(decRoman(1999)) ;MCMXCIX
PrintN(decRoman(1666)) ;MDCLXVI
PrintN(decRoman(25))   ;XXV
PrintN(decRoman(954))  ;CMLIV

Print(#CRLF$+ #CRLF$ + "Press ENTER to exit")
Input()
CloseConsole()
EndIf


### QBasic

DIM SHARED arabic(0 TO 12)
DIM SHARED roman$(0 TO 12) FUNCTION toRoman$ (value)
LET result$= "" FOR i = 0 TO 12 DO WHILE value >= arabic(i) LET result$ = result$+ roman$(i)
LET value = value - arabic(i)
LOOP
NEXT i
toRoman$= result$
END FUNCTION

FOR i = 0 TO 12
READ arabic(i), roman$(i) NEXT i DATA 1000, "M", 900, "CM", 500, "D", 400, "CD", 100, "C", 90, "XC" DATA 50, "L", 40, "XL", 10, "X", 9, "IX", 5, "V", 4, "IV", 1, "I" 'Testing PRINT "2009 = "; toRoman$(2009)
PRINT "1666 = "; toRoman$(1666) PRINT "3888 = "; toRoman$(3888)


### Run BASIC

[loop]
input "Input value:";val$print roman$(val$) goto [loop] ' ------------------------------ ' Roman numerals ' ------------------------------ FUNCTION roman$(val$) a2r$ = "M:1000,CM:900,D:500,CD:400,C:100,XC:90,L:50,XL:40,X:10,IX:9,V:5,IV:4,I:1"
v = val(val$) for i = 1 to 13 r$  = word$(a2r$,i,",")
a   = val(word$(r$,2,":"))
while v >= a
roman$= roman$ + word$(r$,1,":")
v      = v - a
wend
next i
END FUNCTION

### TI-83 BASIC

PROGRAM:DEC2ROM
:"="→Str1
:Lbl ST
:ClrHome
:Disp "NUMBER TO"
:Disp "CONVERT:"
:Input A
:If fPart(A) or A≠abs(A)
:Then
:Goto PI
:End
:A→B
:While B≥1000
:Str1+"M"→Str1
:B-1000→B
:End
:If B≥900
:Then
:Str1+"CM"→Str1
:B-900→B
:End
:If B≥500
:Then
:Str1+"D"→Str1
:B-500→B
:End
:If B≥400
:Then
:Str1+"CD"?Str1
:B-400→B
:End
:While B≥100
:Str1+"C"→Str1
:B-100→B
:End
:If B≥90
:Then
:Str1+"XC"→Str1
:B-90→B
:End
:If B≥50
:Then
:Str1+"L"→Str1
:B-50→B
:End
:If B≥40
:Then
:Str1+"XL"→Str1
:B-40→B
:End
:While B≥10
:Str1+"X"→Str1
:B-10→B
:End
:If B≥9
:Then
:Str1+"IX"→Str1
:B-9→B
:End
:If B≥5
:Then
:Str1+"V"→Str1
:B-5→B
:End
:If B≥4
:Then
:Str1+"IV"→Str1
:B-4→B
:End
:While B>0
:Str1+"I"→Str1
:B-1→B
:End
:ClrHome
:Disp A
:Disp Str1
:Stop
:Lbl PI
:ClrHome
:Disp "THE NUMBER MUST"
:Disp "BE A POSITIVE"
:Disp "INTEGER."
:Pause
:Goto ST

### True BASIC

OPTION BASE 0
DIM arabic(12), roman$(12) FOR i = 0 to 12 READ arabic(i), roman$(i)
NEXT i

DATA 1000, "M", 900, "CM", 500, "D", 400, "CD", 100, "C", 90, "XC"
DATA 50, "L", 40, "XL", 10, "X", 9, "IX", 5, "V",  4, "IV", 1, "I"

FUNCTION toRoman$(value) LET result$ = ""
FOR i = 0 TO 12
DO WHILE value >= arabic(i)
LET result$= result$ & roman$(i) LET value = value - arabic(i) LOOP NEXT i LET toRoman$ = result$END FUNCTION !Testing PRINT "2009 = "; toRoman$(2009)
PRINT "1666 = "; toRoman$(1666) PRINT "3888 = "; toRoman$(3888)
END


### uBasic/4tH

Translation of: BBC Basic
Push 1, 4, 5, 9, 10, 40, 50, 90, 100, 400, 500, 900, 1000
' Initialize array
For i = 12 To 0 Step -1
@(i) = Pop()
Next
' Calculate and print numbers
Print 1999, : Proc _FNroman (1999)
Print 2014, : Proc _FNroman (2014)
Print 1666, : Proc _FNroman (1666)
Print 3888, : Proc _FNroman (3888)

End

_FNroman Param (1)                     ' ( n --)
Local (1)                            ' Define b@
' Try all numbers in array
For b@ = 12 To 0 Step -1
Do While a@ > @(b@) - 1            ' Several occurences of same number?
GoSub ((b@ + 1) * 10)            ' Print roman digit
a@ = a@ - @(b@)                  ' Decrement number
Loop
Next

Print                                ' Terminate line
Return
' Print roman digits
10 Print "I";  : Return
20 Print "IV"; : Return
30 Print "V";  : Return
40 Print "IX"; : Return
50 Print "X";  : Return
60 Print "XL"; : Return
70 Print "L";  : Return
80 Print "XC"; : Return
90 Print "C";  : Return
100 Print "CD"; : Return
110 Print "D";  : Return
120 Print "CM"; : Return
130 Print "M";  : Return


### Visual Basic

Translation of: BASIC
Function toRoman(value) As String
Dim arabic As Variant
Dim roman As Variant

arabic = Array(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1)
roman = Array("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I")

Dim i As Integer, result As String

For i = 0 To 12
Do While value >= arabic(i)
result = result + roman(i)
value = value - arabic(i)
Loop
Next i

toRoman = result
End Function

Sub Main()
End Sub


### XBasic

Translation of: DWScript
Works with: Windows XBasic
PROGRAM "romanenc"
VERSION "0.0000"

DECLARE FUNCTION Entry()
INTERNAL FUNCTION ToRoman$(aValue%%) ' 3888 or MMMDCCCLXXXVIII (15 chars) is the longest string properly encoded with these symbols. FUNCTION Entry() PRINT ToRoman$(1990) ' MCMXC
PRINT ToRoman$(2018) ' MMXVIII PRINT ToRoman$(3888) ' MMMDCCCLXXXVIII
END FUNCTION

FUNCTION ToRoman$(aValue%%) DIM weights%%[12] DIM symbols$[12]

weights%%[0] = 1000
weights%%[1] = 900
weights%%[2] = 500
weights%%[3] = 400
weights%%[4] = 100
weights%%[5] = 90
weights%%[6] = 50
weights%%[7] = 40
weights%%[8] = 10
weights%%[9] = 9
weights%%[10] = 5
weights%%[11] = 4
weights%%[12] = 1

symbols$[0] = "M" symbols$[1] = "CM"
symbols$[2] = "D" symbols$[3] = "CD"
symbols$[4] = "C" symbols$[5] = "XC"
symbols$[6] = "L" symbols$[7] = "XL"
symbols$[8] = "X" symbols$[9] = "IX"
symbols$[10] = "V" symbols$[11] = "IV"
symbols$[12] = "I" destination$ = ""
i@@ = 0
DO WHILE (i@@ <= 12) AND (aValue%% > 0)
DO WHILE aValue%% >= weights%%[i@@]
destination$= destination$ + symbols$[i@@] aValue%% = aValue%% - weights%%[i@@] LOOP i@@ = i@@ + 1 LOOP RETURN destination$
END FUNCTION
END PROGRAM

Output:
MCMXC
MMXVIII
MMMDCCCLXXXVIII


### Yabasic

roman$= "M, CM, D, CD, C, XC, L, XL, X, IX, V, IV, I" decml$ = "1000, 900, 500, 400, 100, 90, 50,  40,  10,  9,  5,   4,  1"

sub toRoman$(value) local res$, i, roman$(1), decml$(1), long

long = token(roman$, roman$(), ", ")
long = token(decml$, decml$(), ", ")

for i=1 to long
while(value >= val(decml$(i))) res$ = res$+ roman$(i)
value = value - val(decml$(i)) wend next i return res$
end sub

print 400, " ", toRoman$(400) print 1990, " ", toRoman$(1990)
print 2008, " ", toRoman$(2008) print 2009, " ", toRoman$(2009)
print 1666, " ", toRoman$(1666) print 3888, " ", toRoman$(3888)
//Output:
// 400 = CD
// 1990 = MCMXC
// 2008 = MMVIII
// 2009 = MMIX
// 1666 = MDCLXVI
// 3888 = MMMDCCCLXXXVIII

### ZX Spectrum Basic

 10 DATA 1000,"M",900,"CM"
20 DATA 500,"D",400,"CD"
30 DATA 100,"C",90,"XC"
40 DATA 50,"L",40,"XL"
50 DATA 10,"X",9,"IX"
60 DATA 5,"V",4,"IV",1,"I"
70 INPUT "Enter an arabic number: ";V
80 LET VALUE=V
90 LET V$="" 100 FOR I=0 TO 12 110 READ A,R$
120 IF V<A THEN GO TO 160
130 LET V$=V$+R$140 LET V=V-A 150 GO TO 120 160 NEXT I 170 PRINT VALUE;"=";V$


## Batch File

Translation of: BASIC
@echo off
setlocal enabledelayedexpansion

set cnt=0&for %%A in (1000,900,500,400,100,90,50,40,10,9,5,4,1) do (set arab!cnt!=%%A&set /a cnt+=1)
set cnt=0&for %%R in (M,CM,D,CD,C,XC,L,XL,X,IX,V,IV,I) do (set rom!cnt!=%%R&set /a cnt+=1)

::Testing
call :toRoman 2009
echo 2009 = !result!
call :toRoman 1666
echo 1666 = !result!
call :toRoman 3888
echo 3888 = !result!
pause>nul
exit/b 0

::The "function"...
:toRoman
set value=%1
set result=

for /l %%i in (0,1,12) do (
set a=%%i
)
goto :EOF

if !value! lss !arab%a%! goto :EOF
set result=!result!!rom%a%!
set /a value-=!arab%a%!

Output:
2009 = MMIX
1666 = MDCLXVI
3888 = MMMDCCCLXXXVIII

## BCPL

get "libhdr"

let toroman(n, v) = valof
$( let extract(n, val, rmn, v) = valof$(  while n >= val
$( n := n - val; for i=1 to rmn%0 do v%(v%0+i) := rmn%i v%0 := v%0 + rmn%0$)
resultis n
$) v%0 := 0 n := extract(n, 1000, "M", v) n := extract(n, 900, "CM", v) n := extract(n, 500, "D", v) n := extract(n, 400, "CD", v) n := extract(n, 100, "C", v) n := extract(n, 90, "XC", v) n := extract(n, 50, "L", v) n := extract(n, 40, "XL", v) n := extract(n, 10, "X", v) n := extract(n, 9, "IX", v) n := extract(n, 5, "V", v) n := extract(n, 4, "IV", v) n := extract(n, 1, "I", v) resultis v$)

let show(n) be
$( let v = vec 50 writef("%I4 = %S*N", n, toroman(n, v))$)

let start() be
$( show(1666) show(2008) show(1001) show(1999) show(3888) show(2021)$)
Output:
1666 = MDCLXVI
2008 = MMVIII
1001 = MI
1999 = MCMXCIX
3888 = MMMDCCCLXXXVIII
2021 = MMXXI

## Befunge

Reads the number to convert from standard input. No range validation is performed.

&>0\0>00p:#v_$>:#,_$ @
4-v >5+#:/#<\55+%:5/\5%:
vv_$9+00g+5g\00g8+>5g\00 g>\20p>:10p00g \#v _20gv > 2+ v^-1g01\g5+8<^ +9 _ IVXLCDM  Output: 1666 MDCLXVI ## BQN Translation of: APL ⟨ToRoman⇐R⟩ ← { ds ← 1↓¨(¯1+⊏⊸=)⊸⊔" I IV V IX X XL L XC C CD D CM M" vs ← 1e3∾˜ ⥊1‿4‿5‿9×⌜˜10⋆↕3 R ⇐ { 𝕨𝕊0: ""; (⊑⟜ds∾·𝕊𝕩-⊑⟜vs) 1-˜⊑vs⍋𝕩 } }  Example use:  ToRoman¨ 1990‿2008‿1666‿2021 ⟨ "MCMXC" "MMVIII" "MDCLXVI" "MMXXI" ⟩  ## Bracmat ( ( encode = indian roman cifr tenfoldroman letter tenfold . !arg:#?indian & :?roman & whl ' ( @(!indian:#%?cifr ?indian) & :?tenfoldroman & whl ' ( !roman:%?letter ?roman & !tenfoldroman ( (I.X) (V.L) (X.C) (L.D) (C.M) : ? (!letter.?tenfold) ? & !tenfold | "*" ) : ?tenfoldroman ) & !tenfoldroman:?roman & ( !cifr:9&!roman I X:?roman | !cifr:~<4 & !roman (!cifr:4&I|) V : ?roman & !cifr+-5:?cifr & ~ | whl ' ( !cifr+-1:~<0:?cifr & !roman I:?roman ) ) ) & ( !roman:? "*" ?&~ | str$!roman
)
)
& 1990 2008 1666 3888 3999 4000:?NS
&   whl
' ( !NS:%?N ?NS
&   out
$( encode$!N:?K&!N !K
| str$("Can't convert " !N " to Roman numeral") ) ) ); Output: 1990 MCMXC 2008 MMVIII 1666 MDCLXVI 3888 MMMDCCCLXXXVIII 3999 MMMCMXCIX Can't convert 4000 to Roman numeral ## C ### Naive solution This solution is a smart but does not return the number written as a string. #include <stdio.h> int main() { int arabic[] = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1}; // There is a bug: "XL\0" is translated into sequence 58 4C 00 00, i.e. it is 4-bytes long... // Should be "XL" without \0 etc. // char roman[13][3] = {"M\0", "CM\0", "D\0", "CD\0", "C\0", "XC\0", "L\0", "XL\0", "X\0", "IX\0", "V\0", "IV\0", "I\0"}; int N; printf("Enter arabic number:\n"); scanf("%d", &N); printf("\nRoman number:\n"); for (int i = 0; i < 13; i++) { while (N >= arabic[i]) { printf("%s", roman[i]); N -= arabic[i]; } } return 0; }  Output: Enter arabic number: 215 Roman number: CCXV  ### Not thread-safe #define _CRT_SECURE_NO_WARNINGS #include <stdio.h> #include <string.h> int RomanNumerals_parseInt(const char* string) { int value; return scanf("%u", &value) == 1 && value > 0 ? value : 0; } const char* RomanNumerals_toString(int value) { #define ROMAN_NUMERALS_MAX_OUTPUT_STRING_SIZE 64 static buffer[ROMAN_NUMERALS_MAX_OUTPUT_STRING_SIZE]; const static int maxValue = 5000; const static int minValue = 1; const static struct Digit { char string[4]; // It's better to use 4 than 3 (aligment). int value; } digits[] = { {"M", 1000}, {"CM", 900}, {"D", 500 }, {"CD", 400 }, {"C", 100 }, {"XC", 90 }, {"L", 50 }, {"XL", 40}, {"X", 10}, {"IX", 9}, {"V", 5}, {"IV", 4}, {"I", 1 }, {"?", 0} }; *buffer = '\0'; // faster than memset(buffer, 0, sizeof(buffer)); if (minValue <= value && value <= maxValue) { struct Digit* digit = &digits[0]; while (digit->value) { while (value >= digit->value) { value -= digit->value; // It is not necessary - total length would not be exceeded... // if (strlen(buffer) + strlen(digit->string) < sizeof(buffer)) strcat(buffer, digit->string); } digit++; } } return buffer; } int main(int argc, char* argv[]) { if (argc < 2) { // Blanks are needed for a consistient blackground on some systems. // BTW, puts append an extra newline at the end. // puts("Write given numbers as Roman numerals. \n" " \n" "Usage: \n" " roman n1 n2 n3 ... \n" " \n" "where n1 n2 n3 etc. are Arabic numerals\n"); int numbers[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1498, 2022 }; for (int i = 0; i < sizeof(numbers) / sizeof(int); i++) { printf("%4d = %s\n", numbers[i], RomanNumerals_toString(numbers[i])); } } else { for (int i = 1; i < argc; i++) { int number = RomanNumerals_parseInt(argv[i]); if (number) { puts(RomanNumerals_toString(number)); } else { puts("???"); } } } return 0; }  Output: Write given numbers as Roman numerals. Usage: roman n1 n2 n3 ... where n1 n2 n3 etc. are Arabic numerals 1 = I 2 = II 3 = III 4 = IV 5 = V 6 = VI 7 = VII 8 = VIII 9 = IX 10 = X 1498 = MCDXCVIII 2022 = MMXXII ## C# using System; class Program { static uint[] nums = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 }; static string[] rum = { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" }; static string ToRoman(uint number) { string value = ""; for (int i = 0; i < nums.Length && number != 0; i++) { while (number >= nums[i]) { number -= nums[i]; value += rum[i]; } } return value; } static void Main() { for (uint number = 1; number <= 1 << 10; number *= 2) { Console.WriteLine("{0} = {1}", number, ToRoman(number)); } } }  One-liner Mono REPL Func<int, string> toRoman = (number) => new Dictionary<int, string> { {1000, "M"}, {900, "CM"}, {500, "D"}, {400, "CD"}, {100, "C"}, {90, "XC"}, {50, "L"}, {40, "XL"}, {10, "X"}, {9, "IX"}, {5, "V"}, {4, "IV"}, {1, "I"} }.Aggregate(new string('I', number), (m, _) => m.Replace(new string('I', _.Key), _.Value));  Output: 1 = I 2 = II 4 = IV 8 = VIII 16 = XVI 32 = XXXII 64 = LXIV 128 = CXXVIII 256 = CCLVI 512 = DXII 1024 = MXXIV  ## C++ ### C++ 98 #include <iostream> #include <string> std::string to_roman(int value) { struct romandata_t { int value; char const* numeral; }; static romandata_t const romandata[] = { 1000, "M", 900, "CM", 500, "D", 400, "CD", 100, "C", 90, "XC", 50, "L", 40, "XL", 10, "X", 9, "IX", 5, "V", 4, "IV", 1, "I", 0, NULL }; // end marker std::string result; for (romandata_t const* current = romandata; current->value > 0; ++current) { while (value >= current->value) { result += current->numeral; value -= current->value; } } return result; } int main() { for (int i = 1; i <= 4000; ++i) { std::cout << to_roman(i) << std::endl; } }  ### C++ 11 #include <iostream> #include <string> std::string to_roman(int x) { if (x <= 0) return "Negative or zero!"; auto roman_digit = [](char one, char five, char ten, int x) { if (x <= 3) return std::string().assign(x, one); if (x <= 5) return std::string().assign(5 - x, one) + five; if (x <= 8) return five + std::string().assign(x - 5, one); return std::string().assign(10 - x, one) + ten; }; if (x >= 1000) return x - 1000 > 0 ? "M" + to_roman(x - 1000) : "M"; if (x >= 100) { auto s = roman_digit('C', 'D', 'M', x / 100); return x % 100 > 0 ? s + to_roman(x % 100) : s; } if (x >= 10) { auto s = roman_digit('X', 'L', 'C', x / 10); return x % 10 > 0 ? s + to_roman(x % 10) : s; } return roman_digit('I', 'V', 'X', x); } int main() { for (int i = 0; i < 2018; i++) std::cout << i << " --> " << to_roman(i) << std::endl; }  ## Ceylon shared void run() { class Numeral(shared Character char, shared Integer int) {} value tiers = [ [Numeral('I', 1), Numeral('V', 5), Numeral('X', 10)], [Numeral('X', 10), Numeral('L', 50), Numeral('C', 100)], [Numeral('C', 100), Numeral('D', 500), Numeral('M', 1k)] ]; String toRoman(Integer hindu, Integer tierIndex = 2) { assert (exists tier = tiers[tierIndex]); " Finds if it's a two character numeral like iv, ix, xl, xc, cd and cm." function findTwoCharacterNumeral() => if (exists bigNum = tier.rest.find((numeral) => numeral.int - tier.first.int <= hindu < numeral.int)) then [tier.first, bigNum] else null; if (hindu <= 0) { // if it's zero then we are done! return ""; } else if (exists [smallNum, bigNum] = findTwoCharacterNumeral()) { value twoCharSymbol = "smallNum.charbigNum.char"; value twoCharValue = bigNum.int - smallNum.int; return "twoCharSymboltoRoman(hindu - twoCharValue, tierIndex)"; } else if (exists num = tier.reversed.find((Numeral elem) => hindu >= elem.int)) { return "num.chartoRoman(hindu - num.int, tierIndex)"; } else { // nothing was found so move to the next smaller tier! return toRoman(hindu, tierIndex - 1); } } assert (toRoman(1) == "I"); assert (toRoman(2) == "II"); assert (toRoman(4) == "IV"); assert (toRoman(1666) == "MDCLXVI"); assert (toRoman(1990) == "MCMXC"); assert (toRoman(2008) == "MMVIII"); }  ## Clojure The easiest way is to use the built-in cl-format function (def arabic->roman (partial clojure.pprint/cl-format nil "~@R")) (arabic->roman 147) ;"CXXIII" (arabic->roman 99) ;"XCIX"  Alternatively: (def roman-map (sorted-map 1 "I", 4 "IV", 5 "V", 9 "IX", 10 "X", 40 "XL", 50 "L", 90 "XC", 100 "C", 400 "CD", 500 "D", 900 "CM" 1000 "M")) (defn int->roman [n] {:pre (integer? n)} (loop [res (StringBuilder.), n n] (if-let [v (roman-map n)] (str (.append res v)) (let [[k v] (->> roman-map keys (filter #(> n %)) last (find roman-map))] (recur (.append res v) (- n k)))))) (int->roman 1999) ; "MCMXCIX"  An alternate implementation: (defn a2r [a] (let [rv '(1000 500 100 50 10 5 1) rm (zipmap rv "MDCLXVI") dv (->> rv (take-nth 2) next #(interleave % %))] (loop [a a rv rv dv dv r nil] (if (<= a 0) r (let [v (first rv) d (or (first dv) 0) l (- v d)] (cond (= a v) (str r (rm v)) (= a l) (str r (rm d) (rm v)) (and (> a v) (> a l)) (recur (- a v) rv dv (str r (rm v))) (and (< a v) (< a l)) (recur a (rest rv) (rest dv) r) :else (recur (- a l) (rest rv) (rest dv) (str r (rm d) (rm v)))))))))  Usage: (a2r 1666) "MDCLXVI" (map a2r [1000 1 389 45]) ("M" "I" "CCCLXXXIX" "XLV")  An alternate implementation: (def roman-map (sorted-map-by > 1 "I", 4 "IV", 5 "V", 9 "IX", 10 "X", 40 "XL", 50 "L", 90 "XC", 100 "C", 400 "CD", 500 "D", 900 "CM" 1000 "M")) (defn a2r ([r] (reduce str (a2r r (keys roman-map)))) ([r n] (when-not (empty? n) (let [e (first n) v (- r e) roman (roman-map e)] (cond (< v 0) (a2r r (rest n)) (= v 0) (cons roman []) (>= v e) (cons roman (a2r v n)) (< v e) (cons roman (a2r v (rest n))))))))  Usage: (a2r 1666) "MDCLXVI" (map a2r [1000 1 389 45]) ("M" "I" "CCCLXXXIX" "XLV")  ## CLU roman = cluster is encode rep = null dmap = struct[v: int, s: string] darr = array[dmap] own chunks: darr := darr$
[dmap${v: 1000, s: "M"}, dmap${v:  900, s: "CM"},
dmap${v: 500, s: "D"}, dmap${v:  400, s: "CD"},
dmap${v: 100, s: "C"}, dmap${v:   90, s: "XC"},
dmap${v: 50, s: "L"}, dmap${v:   40, s: "XL"},
dmap${v: 10, s: "X"}, dmap${v:    9, s: "IX"},
dmap${v: 5, s: "V"}, dmap${v:    4, s: "IV"},
dmap${v: 1, s: "I"}] largest_chunk = proc (i: int) returns (int, string) for chunk: dmap in darr$elements(chunks) do
if chunk.v <= i then return (chunk.v, chunk.s) end
end
return (0, "")
end largest_chunk

encode = proc (i: int) returns (string)
result: string := ""
while i > 0 do
val: int chunk: string
val, chunk := largest_chunk(i)
result := result || chunk
i := i - val
end
return (result)
end encode
end roman

start_up = proc ()
po: stream := stream$primary_output() tests: array[int] := array[int]$[1666, 2008, 1001, 1999, 3888, 2021]

for test: int in array[int]$elements(tests) do stream$putl(po, int$unparse(test) || " = " || roman$encode(test))
end
end start_up
Output:
1666 = MDCLXVI
2008 = MMVIII
1001 = MI
1999 = MCMXCIX
3888 = MMMDCCCLXXXVIII
2021 = MMXXI

## COBOL

IDENTIFICATION DIVISION.
PROGRAM-ID. TOROMAN.
DATA DIVISION.
working-storage section.
01 ws-number pic 9(4) value 0.
01 ws-save-number pic 9(4).
01 ws-tbl-def.
03 filler pic x(7) value '1000M  '.
03 filler pic x(7) value '0900CM '.
03 filler pic x(7) value '0500D  '.
03 filler pic x(7) value '0400CD '.
03 filler pic x(7) value '0100C  '.
03 filler pic x(7) value '0090XC '.
03 filler pic x(7) value '0050L  '.
03 filler pic x(7) value '0040XL '.
03 filler pic x(7) value '0010X  '.
03 filler pic x(7) value '0009IX '.
03 filler pic x(7) value '0005V  '.
03 filler pic x(7) value '0004IV '.
03 filler pic x(7) value '0001I  '.
01  filler redefines ws-tbl-def.
03 filler occurs 13 times indexed by rx.
05 ws-tbl-divisor    pic 9(4).
05 ws-tbl-roman-ch   pic x(1) occurs 3 times indexed by cx.
01 ocx pic 99.
01 ws-roman.
03 ws-roman-ch         pic x(1) occurs 16 times.
PROCEDURE DIVISION.
accept ws-number
perform
until ws-number = 0
move ws-number to ws-save-number
if ws-number > 0 and ws-number < 4000
initialize ws-roman
move 0 to ocx
perform varying rx from 1 by +1
until ws-number = 0
perform until ws-number < ws-tbl-divisor (rx)
perform varying cx from 1 by +1
until ws-tbl-roman-ch (rx, cx) = spaces
compute ocx = ocx + 1
move ws-tbl-roman-ch (rx, cx) to ws-roman-ch (ocx)
end-perform
compute ws-number = ws-number - ws-tbl-divisor (rx)
end-perform
end-perform
display 'inp=' ws-save-number ' roman=' ws-roman
else
display 'inp=' ws-save-number ' invalid'
end-if
accept ws-number
end-perform
.

Output:

(input was supplied via STDIN)

inp=0111 roman=CXI
inp=2234 roman=MMCCXXXIV
inp=0501 roman=DI
inp=0010 roman=X
inp=0040 roman=XL
inp=0050 roman=L
inp=0066 roman=LXVI
inp=0666 roman=DCLXVI
inp=5666 invalid
inp=3333 roman=MMMCCCXXXIII
inp=3888 roman=MMMDCCCLXXXVIII
inp=3999 roman=MMMCMXCIX
inp=3345 roman=MMMCCCXLV


## CoffeeScript

decimal_to_roman = (n) ->
# This should work for any positive integer, although it
# gets a bit preposterous for large numbers.
if n >= 4000
thousands = decimal_to_roman n / 1000
ones = decimal_to_roman n % 1000
return "M(#{thousands})#{ones}"

s = ''
translate_each = (min, roman) ->
while n >= min
n -= min
s += roman
translate_each 1000, "M"
translate_each  900, "CM"
translate_each  500, "D"
translate_each  400, "CD"
translate_each  100, "C"
translate_each   90, "XC"
translate_each   50, "L"
translate_each   40, "XL"
translate_each   10, "X"
translate_each    9, "IX"
translate_each    5, "V"
translate_each    4, "IV"
translate_each    1, "I"
s

###################
tests =
IV: 4
XLII: 42
MCMXC: 1990
MMVIII: 2008
MDCLXVI: 1666
'M(IV)': 4000
'M(VI)IX': 6009
'M(M(CXXIII)CDLVI)DCCLXXXIX': 123456789
'M(MMMV)I': 3005001

for expected, decimal of tests
roman = decimal_to_roman(decimal)
if roman == expected
console.log "#{decimal} = #{roman}"
else
console.log "error for #{decimal}: #{roman} is wrong"


## Common Lisp

(defun roman-numeral (n)
(format nil "~@R" n))


## Cowgol

include "cowgol.coh";
include "argv.coh";

# Encode the given number as a Roman numeral
sub decimalToRoman(num: uint16, buf: [uint8]): (rslt: [uint8]) is
# return the start of the buffer for easy printing
rslt := buf;

while [str] != 0 loop
[buf] := [str];
buf := @next buf;
str := @next str;
end loop;
end sub;

# Table of Roman numerals
record Roman is
value: uint16;
string: [uint8];
end record;

var numerals: Roman[] := {
{1000, "M"}, {900, "CM"}, {500, "D"}, {400, "CD"},
{100, "C"}, {90, "XC"}, {50, "L"}, {40, "XL"},
{10, "X"}, {9, "IX"}, {5, "V"}, {4, "IV"},
{1, "I"}
};

var curNum := &numerals as [Roman];
while num != 0 loop
while num >= curNum.value loop
num := num - curNum.value;
end loop;
curNum := @next curNum;
end loop;

[buf] := 0; # terminate the string
end sub;

# Read numbers from the command line and print the corresponding Roman numerals
ArgvInit();
var buffer: uint8[100];
loop
var argmt := ArgvNext();
if argmt == (0 as [uint8]) then
break;
end if;

var dummy: [uint8];
var number: int32;
(number, dummy) := AToI(argmt);

print(decimalToRoman(number as uint16, &buffer as [uint8]));
print_nl();
end loop;
Output:
$./romanenc.386 1990 2008 1666 MCMXC MMVIII MDCLXVI ## D string toRoman(int n) pure nothrow in { assert(n < 5000); } body { static immutable weights = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]; static immutable symbols = ["M","CM","D","CD","C","XC","L", "XL","X","IX","V","IV","I"]; string roman; foreach (i, w; weights) { while (n >= w) { roman ~= symbols[i]; n -= w; } if (n == 0) break; } return roman; } unittest { assert(toRoman(455) == "CDLV"); assert(toRoman(3456) == "MMMCDLVI"); assert(toRoman(2488) == "MMCDLXXXVIII"); } void main() {}  ## Delphi Translation of: DWScript program RomanNumeralsEncode; {$APPTYPE CONSOLE}

function IntegerToRoman(aValue: Integer): string;
var
i: Integer;
const
WEIGHTS: array[0..12] of Integer = (1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1);
SYMBOLS: array[0..12] of string = ('M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I');
begin
for i := Low(WEIGHTS) to High(WEIGHTS) do
begin
while aValue >= WEIGHTS[i] do
begin
Result := Result + SYMBOLS[i];
aValue := aValue - WEIGHTS[i];
end;
if aValue = 0 then
Break;
end;
end;

begin
Writeln(IntegerToRoman(1990)); // MCMXC
Writeln(IntegerToRoman(2008)); // MMVIII
Writeln(IntegerToRoman(1666)); // MDCLXVI
end.


## DWScript

Translation of: D
const weights = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1];
const symbols = ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"];

function toRoman(n : Integer) : String;
var
i, w : Integer;
begin
for i := 0 to weights.High do begin
w := weights[i];
while n >= w do begin
Result += symbols[i];
n -= w;
end;
if n = 0 then Break;
end;
end;

PrintLn(toRoman(455));
PrintLn(toRoman(3456));
PrintLn(toRoman(2488));


## EasyLang

func$dec2rom dec . values[] = [ 1000 900 500 400 100 90 50 40 10 9 5 4 1 ] symbol$[] = [ "M" "CM" "D" "CD" "C" "XC" "L" "XL" "X" "IX" "V" "IV" "I" ]
for i = 1 to len values[]
while dec >= values[i]
rom$&= symbol$[i]
dec -= values[i]
.
.
return rom$. print dec2rom 1990 print dec2rom 2008 print dec2rom 1666  ## ECL RomanEncode(UNSIGNED Int) := FUNCTION SetWeights := [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]; SetSymbols := ['M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I']; ProcessRec := RECORD UNSIGNED val; STRING Roman; END; dsWeights := DATASET(13,TRANSFORM(ProcessRec,SELF.val := Int, SELF := [])); SymbolStr(i,n,STRING s) := CHOOSE(n+1,'',SetSymbols[i],SetSymbols[i]+SetSymbols[i],SetSymbols[i]+SetSymbols[i]+SetSymbols[i],s); RECORDOF(dsWeights) XF(dsWeights L, dsWeights R, INTEGER C) := TRANSFORM ThisVal := IF(C=1,R.Val,L.Val); IsDone := ThisVal = 0; SELF.Roman := IF(IsDone,L.Roman,L.Roman + SymbolStr(C,ThisVal DIV SetWeights[C],L.Roman)); SELF.val := IF(IsDone,0,ThisVal - ((ThisVal DIV SetWeights[C])*SetWeights[C])); END; i := ITERATE(dsWeights,XF(LEFT,RIGHT,COUNTER)); RETURN i[13].Roman; END; RomanEncode(1954); //MCMLIV RomanEncode(1990 ); //MCMXC RomanEncode(2008 ); //MMVIII RomanEncode(1666); //MDCLXVI  ## Ed H g/0([0-9]{3})/s//\1/ g/1([0-9]{3})/s//M\1/ g/2([0-9]{3})/s//MM\1/ g/3([0-9]{3})/s//MMM\1/ g/4([0-9]{3})/s//MMMM\1/ g/0([0-9]{2})/s//\1/ g/1([0-9]{2})/s//C\1/ g/2([0-9]{2})/s//CC\1/ g/3([0-9]{2})/s//CCC\1/ g/4([0-9]{2})/s//CD\1/ g/5([0-9]{2})/s//D\1/ g/6([0-9]{2})/s//DC\1/ g/7([0-9]{2})/s//DCC\1/ g/8([0-9]{2})/s//DCCC\1/ g/9([0-9]{2})/s//CM\1/ g/0([0-9]{2})/s//\1/ g/1([0-9]{1})/s//X\1/ g/2([0-9]{1})/s//XX\1/ g/3([0-9]{1})/s//XXX\1/ g/4([0-9]{1})/s//XL\1/ g/5([0-9]{1})/s//L\1/ g/6([0-9]{1})/s//LX\1/ g/7([0-9]{1})/s//LXX\1/ g/8([0-9]{1})/s//LXXX\1/ g/9([0-9]{1})/s//XC\1/ g/0([0-9]{1})/s//\1/ g/1/s//I/ g/2/s//II/ g/3/s//III/ g/4/s//IV/ g/5/s//V/ g/6/s//VI/ g/7/s//VII/ g/8/s//VIII/ g/9/s//IX/ g/0/s/// ,p Q ## Eiffel class APPLICATION create make feature {NONE} -- Initialization make local numbers: ARRAY [INTEGER] do numbers := <<1990, 2008, 1666, 3159, 1977, 2010>> -- "MCMXC", "MMVIII", "MDCLXVI", "MMMCLIX", "MCMLXXVII", "MMX" across numbers as n loop print (n.item.out + " in decimal Arabic numerals is " + decimal_to_roman (n.item) + " in Roman numerals.%N") end end feature -- Roman numerals decimal_to_roman (a_int: INTEGER): STRING -- Representation of integer a_int' as Roman numeral require a_int > 0 local dnums: ARRAY[INTEGER] rnums: ARRAY[STRING] dnum: INTEGER rnum: STRING i: INTEGER do dnums := <<1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1>> rnums := <<"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I">> dnum := a_int rnum := "" from i := 1 until i > dnums.count or dnum <= 0 loop from until dnum < dnums[i] loop dnum := dnum - dnums[i] rnum := rnum + rnums[i] end i := i + 1 end Result := rnum end end  ## Ela Translation of: Haskell open number string math digit x y z k = [[x],[x,x],[x,x,x],[x,y],[y],[y,x],[y,x,x],[y,x,x,x],[x,z]] : (toInt k - 1) toRoman 0 = "" toRoman x | x < 0 = fail "Negative roman numeral" | x >= 1000 = 'M' :: toRoman (x - 1000) | x >= 100 = let (q,r) = x divrem 100 in digit 'C' 'D' 'M' q ++ toRoman r | x >= 10 = let (q,r) = x divrem 10 in digit 'X' 'L' 'C' q ++ toRoman r | else = digit 'I' 'V' 'X' x map (join "" << toRoman) [1999,25,944] Output: ["MCMXCIX","XXV","CMXLIV"] ## Elena Translation of: C# ELENA 6.x : import system'collections; import system'routines; import extensions; import extensions'text; static RomanDictionary = Dictionary.new() .setAt(1000, "M") .setAt(900, "CM") .setAt(500, "D") .setAt(400, "CD") .setAt(100, "C") .setAt(90, "XC") .setAt(50, "L") .setAt(40, "XL") .setAt(10, "X") .setAt(9, "IX") .setAt(5, "V") .setAt(4, "IV") .setAt(1, "I"); extension op { toRoman() = RomanDictionary.accumulate(new StringWriter("I", self), (m,kv => m.replace(new StringWriter("I",kv.Key).Value, kv.Value))); } public program() { console.printLine("1990 : ", 1990.toRoman()); console.printLine("2008 : ", 2008.toRoman()); console.printLine("1666 : ", 1666.toRoman()) } Output: 1990 : MCMXC 2008 : MMVIII 1666 : MDCLXVI  ## Elixir Translation of: Erlang defmodule Roman_numeral do def encode(0), do: '' def encode(x) when x >= 1000, do: [?M | encode(x - 1000)] def encode(x) when x >= 100, do: digit(div(x,100), ?C, ?D, ?M) ++ encode(rem(x,100)) def encode(x) when x >= 10, do: digit(div(x,10), ?X, ?L, ?C) ++ encode(rem(x,10)) def encode(x) when x >= 1, do: digit(x, ?I, ?V, ?X) defp digit(1, x, _, _), do: [x] defp digit(2, x, _, _), do: [x, x] defp digit(3, x, _, _), do: [x, x, x] defp digit(4, x, y, _), do: [x, y] defp digit(5, _, y, _), do: [y] defp digit(6, x, y, _), do: [y, x] defp digit(7, x, y, _), do: [y, x, x] defp digit(8, x, y, _), do: [y, x, x, x] defp digit(9, x, _, z), do: [x, z] end  Another: Translation of: Ruby defmodule Roman_numeral do @symbols [ {1000, 'M'}, {900, 'CM'}, {500, 'D'}, {400, 'CD'}, {100, 'C'}, {90, 'XC'}, {50, 'L'}, {40, 'XL'}, {10, 'X'}, {9, 'IX'}, {5, 'V'}, {4, 'IV'}, {1, 'I'} ] def encode(num) do {roman,_} = Enum.reduce(@symbols, {[], num}, fn {divisor, letter}, {memo, n} -> {memo ++ List.duplicate(letter, div(n, divisor)), rem(n, divisor)} end) Enum.join(roman) end end  Test: Enum.each([1990, 2008, 1666], fn n -> IO.puts "#{n}: #{Roman_numeral.encode(n)}" end)  Output: 1990: MCMXC 2008: MMVIII 1666: MDCLXVI  ## Emacs Lisp (defun ar2ro (AN) "Translate from arabic number AN to roman number. For example, (ar2ro 1666) returns (M D C L X V I)." (cond ((>= AN 1000) (cons 'M (ar2ro (- AN 1000)))) ((>= AN 900) (cons 'C (cons 'M (ar2ro (- AN 900))))) ((>= AN 500) (cons 'D (ar2ro (- AN 500)))) ((>= AN 400) (cons 'C (cons 'D (ar2ro (- AN 400))))) ((>= AN 100) (cons 'C (ar2ro (- AN 100)))) ((>= AN 90) (cons 'X (cons 'C (ar2ro (- AN 90))))) ((>= AN 50) (cons 'L (ar2ro (- AN 50)))) ((>= AN 40) (cons 'X (cons 'L (ar2ro (- AN 40))))) ((>= AN 10) (cons 'X (ar2ro (- AN 10)))) ((>= AN 5) (cons 'V (ar2ro (- AN 5)))) ((>= AN 4) (cons 'I (cons 'V (ar2ro (- AN 4))))) ((>= AN 1) (cons 'I (ar2ro (- AN 1)))) ((= AN 0) nil)))  ## Erlang Translation of: OCaml -module(roman). -export([to_roman/1]). to_roman(0) -> []; to_roman(X) when X >= 1000 -> [$M | to_roman(X - 1000)];
to_roman(X) when X >= 100 ->
digit(X div 100, $C,$D, $M) ++ to_roman(X rem 100); to_roman(X) when X >= 10 -> digit(X div 10,$X, $L,$C) ++ to_roman(X rem 10);
to_roman(X) when X >= 1 -> digit(X, $I,$V, $X). digit(1, X, _, _) -> [X]; digit(2, X, _, _) -> [X, X]; digit(3, X, _, _) -> [X, X, X]; digit(4, X, Y, _) -> [X, Y]; digit(5, _, Y, _) -> [Y]; digit(6, X, Y, _) -> [Y, X]; digit(7, X, Y, _) -> [Y, X, X]; digit(8, X, Y, _) -> [Y, X, X, X]; digit(9, X, _, Z) -> [X, Z].  sample: 1> c(roman). {ok,roman} 2> roman:to_roman(1999). "MCMXCIX" 3> roman:to_roman(25). "XXV" 4> roman:to_roman(944). "CMXLIV"  Alternative: -module( roman_numerals ). -export( [encode_from_integer/1]). -record( encode_acc, {n, romans=""} ). encode_from_integer( N ) when N > 0 -> #encode_acc{romans=Romans} = lists:foldl( fun encode_from_integer/2, #encode_acc{n=N}, map() ), Romans. encode_from_integer( _Map, #encode_acc{n=0}=Acc ) -> Acc; encode_from_integer( {_Roman, Value}, #encode_acc{n=N}=Acc ) when N < Value -> Acc; encode_from_integer( {Roman, Value}, #encode_acc{n=N, romans=Romans} ) -> Times = N div Value, New_roman = lists:flatten( lists:duplicate(Times, Roman) ), #encode_acc{n=N - (Times * Value), romans=Romans ++ New_roman}. map() -> [{"M",1000}, {"CM",900}, {"D",500}, {"CD",400}, {"C",100}, {"XC",90}, {"L",50}, {"XL",40}, {"X",10}, {"IX",9}, {"V",5}, {"IV",4}, {"I\ ",1}].  Output: 36> roman_numerals:encode_from_integer( 1990 ). "MCMXC" 37> roman_numerals:encode_from_integer( 2008 ). "MMVIII" 38> roman_numerals:encode_from_integer( 1666 ). "MDCLXVI"  ## ERRE PROGRAM ARAB2ROMAN DIM ARABIC%[12],ROMAN$[12]

PROCEDURE TOROMAN(VALUE->ANS$) LOCAL RESULT$
FOR I%=0 TO 12 DO
WHILE VALUE>=ARABIC%[I%] DO
RESULT$+=ROMAN$[I%]
VALUE-=ARABIC%[I%]
END WHILE
END FOR
ANS$=RESULT$
END PROCEDURE

BEGIN
!
!Testing
!
ARABIC%[]=(1000,900,500,400,100,90,50,40,10,9,5,4,1)
ROMAN$[]=("M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I") TOROMAN(2009->ANS$) PRINT("2009 = ";ANS$) TOROMAN(1666->ANS$) PRINT("1666 = ";ANS$) TOROMAN(3888->ANS$) PRINT("3888 = ";ANS$) END PROGRAM ## Euphoria Translation of: BASIC constant arabic = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 } constant roman = {"M", "CM", "D","CD", "C","XC","L","XL","X","IX","V","IV","I"} function toRoman(integer val) sequence result result = "" for i = 1 to 13 do while val >= arabic[i] do result &= roman[i] val -= arabic[i] end while end for return result end function printf(1,"%d = %s\n",{2009,toRoman(2009)}) printf(1,"%d = %s\n",{1666,toRoman(1666)}) printf(1,"%d = %s\n",{3888,toRoman(3888)}) Output:  2009 = MMIX 1666 = MDCLXVI 3888 = MMMDCCCLXXXVIII  ## Excel Excel can encode numbers in Roman forms in 5 successively concise forms. These can be indicated from 0 to 4. Type in a cell: =ROMAN(2013,0) It becomes: MMXIII  ## F# let digit x y z = function 1 -> x | 2 -> x + x | 3 -> x + x + x | 4 -> x + y | 5 -> y | 6 -> y + x | 7 -> y + x + x | 8 -> y + x + x + x | 9 -> x + z | _ -> failwith "invalid call to digit" let rec to_roman acc = function | x when x >= 1000 -> to_roman (acc + "M") (x - 1000) | x when x >= 100 -> to_roman (acc + digit "C" "D" "M" (x / 100)) (x % 100) | x when x >= 10 -> to_roman (acc + digit "X" "L" "C" (x / 10)) (x % 10) | x when x > 0 -> acc + digit "I" "V" "X" x | 0 -> acc | _ -> failwith "invalid call to_roman (negative input)" let roman n = to_roman "" n [<EntryPoint>] let main args = [1990; 2008; 1666] |> List.map (fun n -> roman n) |> List.iter (printfn "%s") 0  Output: MCMXC MMVIII MDCLXVI ## Factor A roman numeral library ships with Factor. USE: roman ( scratchpad ) 3333 >roman . "mmmcccxxxiii"  Parts of the implementation: CONSTANT: roman-digits { "m" "cm" "d" "cd" "c" "xc" "l" "xl" "x" "ix" "v" "iv" "i" } CONSTANT: roman-values { 1000 900 500 400 100 90 50 40 10 9 5 4 1 } ERROR: roman-range-error n ; : roman-range-check ( n -- n ) dup 1 10000 between? [ roman-range-error ] unless ; : >roman ( n -- str ) roman-range-check roman-values roman-digits [ [ /mod swap ] dip <repetition> concat ] 2map "" concat-as nip ;  ## FALSE ^$." "
[$999>][1000- "M"]#$899> [ 900-"CM"]?
$499> [ 500- "D"]?$399> [ 400-"CD"]?
[$99>][ 100- "C"]#$ 89> [  90-"XC"]?
$49> [ 50- "L"]?$ 39> [  40-"XL"]?
[$9>][ 10- "X"]#$  8> [   9-"IX"]?
$4> [ 5- "V"]?$  3> [   4-"IV"]?
[$][ 1- "I"]#% ## Fan ** ** converts a number to its roman numeral representation ** class RomanNumerals { private Str digit(Str x, Str y, Str z, Int i) { switch (i) { case 1: return x case 2: return x+x case 3: return x+x+x case 4: return x+y case 5: return y case 6: return y+x case 7: return y+x+x case 8: return y+x+x+x case 9: return x+z } return "" } Str toRoman(Int i) { if (i>=1000) { return "M" + toRoman(i-1000) } if (i>=100) { return digit("C", "D", "M", i/100) + toRoman(i%100) } if (i>=10) { return digit("X", "L", "C", i/10) + toRoman(i%10) } if (i>=1) { return digit("I", "V", "X", i) } return "" } Void main() { 2000.times |i| { echo("$i = ${toRoman(i)}") } } }  ## Forth : vector create ( n -- ) 0 do , loop does> ( n -- ) swap cells + @ execute ; \ these are ( numerals -- numerals ) : ,I dup c@ C, ; : ,V dup 1 + c@ C, ; : ,X dup 2 + c@ C, ; \ these are ( numerals -- ) :noname ,I ,X drop ; :noname ,V ,I ,I ,I drop ; :noname ,V ,I ,I drop ; :noname ,V ,I drop ; :noname ,V drop ; :noname ,I ,V drop ; :noname ,I ,I ,I drop ; :noname ,I ,I drop ; :noname ,I drop ; ' drop ( 0 : no output ) 10 vector ,digit : roman-rec ( numerals n -- ) 10 /mod dup if >r over 2 + r> recurse else drop then ,digit ; : roman ( n -- c-addr u ) dup 0 4000 within 0= abort" EX LIMITO!" HERE SWAP s" IVXLCDM" drop swap roman-rec HERE OVER - ; 1999 roman type \ MCMXCIX 25 roman type \ XXV 944 roman type \ CMXLIV  Alternative implementation create romans 0 , 1 , 5 , 21 , 9 , 2 , 6 , 22 , 86 , 13 , does> swap cells + @ ; : roman-digit ( a1 n1 a2 n2 -- a3) drop >r romans begin dup while tuck 4 mod 1- chars r@ + c@ over c! char+ swap 4 / repeat r> drop drop ; : (split) swap >r /mod r> swap ; : >roman ( n1 a -- a n2) tuck 1000 (split) s" M " roman-digit 100 (split) s" CDM" roman-digit 10 (split) s" XLC" roman-digit 1 (split) s" IVX" roman-digit nip over - ; create (roman) 16 chars allot 1999 (roman) >roman type cr  ## Fortran Works with: Fortran version 90 and later program roman_numerals implicit none write (*, '(a)') roman (2009) write (*, '(a)') roman (1666) write (*, '(a)') roman (3888) contains function roman (n) result (r) implicit none integer, intent (in) :: n integer, parameter :: d_max = 13 integer :: d integer :: m integer :: m_div character (32) :: r integer, dimension (d_max), parameter :: d_dec = & & (/1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1/) character (32), dimension (d_max), parameter :: d_rom = & & (/'M ', 'CM', 'D ', 'CD', 'C ', 'XC', 'L ', 'XL', 'X ', 'IX', 'V ', 'IV', 'I '/) r = '' m = n do d = 1, d_max m_div = m / d_dec (d) r = trim (r) // repeat (trim (d_rom (d)), m_div) m = m - d_dec (d) * m_div end do end function roman end program roman_numerals  Output:  MMIX MDCLXVI MMMDCCCLXXXVIII  ## Go For fluff, the unicode overbar is recognized as a factor of 1000, as described in WP. If you see boxes in the code below, those are supposed to be the Unicode combining overline (U+0305) and look like IVXLCDM. Or, if you see overstruck combinations of letters, that's a different font rendering problem. (If you need roman numerals > 3999 reliably, it might best to stick to chiseling them in stone...) package main import "fmt" var ( m0 = []string{"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"} m1 = []string{"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"} m2 = []string{"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"} m3 = []string{"", "M", "MM", "MMM", "I̅V̅", "V̅", "V̅I̅", "V̅I̅I̅", "V̅I̅I̅I̅", "I̅X̅"} m4 = []string{"", "X̅", "X̅X̅", "X̅X̅X̅", "X̅L̅", "L̅", "L̅X̅", "L̅X̅X̅", "L̅X̅X̅X̅", "X̅C̅"} m5 = []string{"", "C̅", "C̅C̅", "C̅C̅C̅", "C̅D̅", "D̅", "D̅C̅", "D̅C̅C̅", "D̅C̅C̅C̅", "C̅M̅"} m6 = []string{"", "M̅", "M̅M̅", "M̅M̅M̅"} ) func formatRoman(n int) (string, bool) { if n < 1 || n >= 4e6 { return "", false } // this is efficient in Go. the seven operands are evaluated, // then a single allocation is made of the exact size needed for the result. return m6[n/1e6] + m5[n%1e6/1e5] + m4[n%1e5/1e4] + m3[n%1e4/1e3] + m2[n%1e3/1e2] + m1[n%100/10] + m0[n%10], true } func main() { // show three numbers mentioned in task descriptions for _, n := range []int{1990, 2008, 1666} { r, ok := formatRoman(n) if ok { fmt.Println(n, "==", r) } else { fmt.Println(n, "not representable") } } }  Output: 1990 == MCMXC 2008 == MMVIII 1666 == MDCLXVI  ## Golo #!/usr/bin/env golosh ---- This module takes a decimal integer and converts it to a Roman numeral. ---- module Romannumeralsencode augment java.lang.Integer { function digits = |this| { var remaining = this let digits = vector[] while remaining > 0 { digits: prepend(remaining % 10) remaining = remaining / 10 } return digits } ---- 123: digitsWithPowers() will return [[1, 2], [2, 1], [3, 0]] ---- function digitsWithPowers = |this| -> vector[ [ this: digits(): get(i), (this: digits(): size() - 1) - i ] for (var i = 0, i < this: digits(): size(), i = i + 1) ] function encode = |this| { require(this > 0, "the integer must be positive!") let romanPattern = |digit, powerOf10| -> match { when digit == 1 then i when digit == 2 then i + i when digit == 3 then i + i + i when digit == 4 then i + v when digit == 5 then v when digit == 6 then v + i when digit == 7 then v + i + i when digit == 8 then v + i + i + i when digit == 9 then i + x otherwise "" } with { i, v, x = [ [ "I", "V", "X" ], [ "X", "L", "C" ], [ "C", "D", "M" ], [ "M", "?", "?" ] ]: get(powerOf10) } return vector[ romanPattern(digit, power) foreach digit, power in this: digitsWithPowers() ]: join("") } } function main = |args| { println("1990 == MCMXC? " + (1990: encode() == "MCMXC")) println("2008 == MMVIII? " + (2008: encode() == "MMVIII")) println("1666 == MDCLXVI? " + (1666: encode() == "MDCLXVI")) }  ## Groovy symbols = [ 1:'I', 4:'IV', 5:'V', 9:'IX', 10:'X', 40:'XL', 50:'L', 90:'XC', 100:'C', 400:'CD', 500:'D', 900:'CM', 1000:'M' ] def roman(arabic) { def result = "" symbols.keySet().sort().reverse().each { while (arabic >= it) { arabic-=it result+=symbols[it] } } return result } assert roman(1) == 'I' assert roman(2) == 'II' assert roman(4) == 'IV' assert roman(8) == 'VIII' assert roman(16) == 'XVI' assert roman(32) == 'XXXII' assert roman(25) == 'XXV' assert roman(64) == 'LXIV' assert roman(128) == 'CXXVIII' assert roman(256) == 'CCLVI' assert roman(512) == 'DXII' assert roman(954) == 'CMLIV' assert roman(1024) == 'MXXIV' assert roman(1666) == 'MDCLXVI' assert roman(1990) == 'MCMXC' assert roman(2008) == 'MMVIII'  ## Haskell With an explicit decimal digit representation list: digit :: Char -> Char -> Char -> Integer -> String digit x y z k = [[x], [x, x], [x, x, x], [x, y], [y], [y, x], [y, x, x], [y, x, x, x], [x, z]] !! (fromInteger k - 1) toRoman :: Integer -> String toRoman 0 = "" toRoman x | x < 0 = error "Negative roman numeral" toRoman x | x >= 1000 = 'M' : toRoman (x - 1000) toRoman x | x >= 100 = digit 'C' 'D' 'M' q ++ toRoman r where (q, r) = x divMod 100 toRoman x | x >= 10 = digit 'X' 'L' 'C' q ++ toRoman r where (q, r) = x divMod 10 toRoman x = digit 'I' 'V' 'X' x main :: IO () main = print$ toRoman <$> [1999, 25, 944]  Output: ["MCMXCIX","XXV","CMXLIV"] or, defining romanFromInt in terms of mapAccumL import Data.Bifunctor (first) import Data.List (mapAccumL) import Data.Tuple (swap) roman :: Int -> String roman = romanFromInt$
zip
[1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
(words "M CM D CD C XC L XL X IX V IV I")

romanFromInt :: [(Int, String)] -> Int -> String
romanFromInt nks n = concat . snd $mapAccumL go n nks where go a (v, s) = swap$ first ((>> s) . enumFromTo 1) $quotRem a v main :: IO () main = (putStrLn . unlines) (roman <$> [1666, 1990, 2008, 2016, 2018])

Output:
MDCLXVI
MCMXC
MMVIII
MMXVI
MMXVIII

With the Roman patterns abstracted, and in a simple logic programming idiom:

module Main where

------------------------
--  ENCODER FUNCTION  --
------------------------

romanDigits = "IVXLCDM"

--  Meaning and indices of the romanDigits sequence:
--
--    magnitude |  1 5  | index
--   -----------|-------|-------
--        0     |  I V  |  0 1
--        1     |  X L  |  2 3
--        2     |  C D  |  4 5
--        3     |  M    |  6
--
--  romanPatterns are index offsets into romanDigits,
--  from an index base of 2 * magnitude.

romanPattern 0 = []      -- empty string
romanPattern 1 = [0]     -- I or X or C or M
romanPattern 2 = [0,0]   -- II or XX...
romanPattern 3 = [0,0,0] -- III...
romanPattern 4 = [0,1]   -- IV...
romanPattern 5 = [1]     -- ...
romanPattern 6 = [1,0]
romanPattern 7 = [1,0,0]
romanPattern 8 = [1,0,0,0]
romanPattern 9 = [0,2]

encodeValue 0 _ = ""
encodeValue value magnitude = encodeValue rest (magnitude + 1) ++ digits
where
low = rem value 10 -- least significant digit (encoded now)
rest = div value 10 -- the other digits (to be encoded next)
indices = map addBase (romanPattern low)
addBase i = i + (2 * magnitude)
digits = map pickDigit indices
pickDigit i = romanDigits!!i

encode value = encodeValue value 0

------------------
--  TEST SUITE  --
------------------

main = do
test "MCMXC" 1990
test "MMVIII" 2008
test "MDCLXVI" 1666

test expected value = putStrLn ((show value) ++ " = " ++ roman ++ remark)
where
roman = encode value
remark =
" (" ++
(if roman == expected then "PASS"
else ("FAIL, expected " ++ (show expected))) ++ ")"

Output:
1990 = MCMXC (PASS)
2008 = MMVIII (PASS)
1666 = MDCLXVI (PASS)


## HicEst

CHARACTER Roman*20

CALL RomanNumeral(1990, Roman) ! MCMXC
CALL RomanNumeral(2008, Roman) ! MMVIII
CALL RomanNumeral(1666, Roman) ! MDCLXVI

END

SUBROUTINE RomanNumeral( arabic, roman)
CHARACTER roman
DIMENSION ddec(13)
DATA      ddec/1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1/

roman = ' '
todo = arabic
DO d = 1, 13
DO rep = 1, todo / ddec(d)
roman = TRIM(roman) // TRIM(CHAR(d, 13, "M  CM D  CD C  XC L  XL X  OX V  IV I  "))
todo = todo - ddec(d)
ENDDO
ENDDO
END

## Hoon

Library file (e.g. /lib/rhonda.hoon):

|%
++  parse
|=  t=tape  ^-  @ud
=.  t  (cass t)
=|  result=@ud
|-
?~  t  result
?~  t.t  (add result (from-numeral i.t))
=+  [a=(from-numeral i.t) b=(from-numeral i.t.t)]
?:  (gte a b)  $(result (add result a), t t.t)$(result (sub (add result b) a), t t.t.t)
++  yield
|=  n=@ud  ^-  tape
=|  result=tape
=/  values  to-numeral
|-
?~  values  result
?:  (gte n -.i.values)
$(result (weld result +.i.values), n (sub n -.i.values))$(values t.values)
++  from-numeral
|=  c=@t  ^-  @ud
?:  =(c 'i')  1
?:  =(c 'v')  5
?:  =(c 'x')  10
?:  =(c 'l')  50
?:  =(c 'c')  100
?:  =(c 'd')  500
?:  =(c 'm')  1.000
!!
++  to-numeral
^-  (list [@ud tape])
:*
[1.000 "m"]
[900 "cm"]
[500 "d"]
[400 "cd"]
[100 "c"]
[90 "xc"]
[50 "l"]
[40 "xl"]
[10 "x"]
[9 "ix"]
[5 "v"]
[4 "iv"]
[1 "i"]
~
==
--

Script file ("generator") (e.g. /gen/roman.hoon):

/+  *roman
:-  %say
ONE SIX SIX SIX

MDCLXVI



## Io

Translation of: C#
Roman := Object clone do (
nums := list(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1)
rum := list("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I")

numeral := method(number,
result := ""
for(i, 0, nums size,
if(number == 0, break)
while(number >= nums at(i),
number = number - nums at(i)
result = result .. rum at(i)
)
)
return result
)
)

Roman numeral(1666) println


## J

rfd obtains Roman numerals from decimals.

R1000=. ;L:1 ,{ <@(<;._1);._2]0 :0
C CC CCC CD D DC DCC DCCC CM
X XX XXX XL L LX LXX LXXX XC
I II III IV V VI VII VIII IX
)

rfd=: ('M' $~ <.@%&1000) , R1000 {::~ 1000&|  Explanation: R1000's definition contains rows representing each of 10 different digits in the 100s, 10s and 1s column (the first entry in each row is blank -- each entry is preceded by a space). R1000 itself represents the first 1000 roman numerals (the cartesian product of these three rows of roman numeral "digits" which is constructed so that they are in numeric order. And the first entry -- zero -- is just blank). To convert a number to its roman numeral representation, we will separate the number into the integer part after dividing by 1000 (that's the number of 'M's we need) and the remainder after dividing by 1000 (which will be an index into R1000). For example:  rfd 1234 MCCXXXIV rfd 567 DLXVII rfd 89 LXXXIX  Derived from the J Wiki. Further examples of use will be found there. ## Java Translation of: Ada The conversion function throws an IllegalArgumentException for non-positive numbers, since Java does not have unsigned primitives. Works with: Java version 1.5+ public class RN { enum Numeral { I(1), IV(4), V(5), IX(9), X(10), XL(40), L(50), XC(90), C(100), CD(400), D(500), CM(900), M(1000); int weight; Numeral(int weight) { this.weight = weight; } }; public static String roman(long n) { if( n <= 0) { throw new IllegalArgumentException(); } StringBuilder buf = new StringBuilder(); final Numeral[] values = Numeral.values(); for (int i = values.length - 1; i >= 0; i--) { while (n >= values[i].weight) { buf.append(values[i]); n -= values[i].weight; } } return buf.toString(); } public static void test(long n) { System.out.println(n + " = " + roman(n)); } public static void main(String[] args) { test(1999); test(25); test(944); test(0); } }  Output: 1999 = MCMXCIX 25 = XXV 944 = CMXLIV Exception in thread "main" java.lang.IllegalArgumentException at RN.roman(RN.java:15) at RN.test(RN.java:31) at RN.main(RN.java:38) Works with: Java version 1.8+ import java.util.Set; import java.util.EnumSet; import java.util.Collections; import java.util.stream.Collectors; import java.util.stream.LongStream; public interface RomanNumerals { public enum Numeral { M(1000), CM(900), D(500), CD(400), C(100), XC(90), L(50), XL(40), X(10), IX(9), V(5), IV(4), I(1); public final long weight; private static final Set<Numeral> SET = Collections.unmodifiableSet(EnumSet.allOf(Numeral.class)); private Numeral(long weight) { this.weight = weight; } public static Numeral getLargest(long weight) { return SET.stream() .filter(numeral -> weight >= numeral.weight) .findFirst() .orElse(I) ; } }; public static String encode(long n) { return LongStream.iterate(n, l -> l - Numeral.getLargest(l).weight) .limit(Numeral.values().length) .filter(l -> l > 0) .mapToObj(Numeral::getLargest) .map(String::valueOf) .collect(Collectors.joining()) ; } public static long decode(String roman) { long result = new StringBuilder(roman.toUpperCase()).reverse().chars() .mapToObj(c -> Character.toString((char) c)) .map(numeral -> Enum.valueOf(Numeral.class, numeral)) .mapToLong(numeral -> numeral.weight) .reduce(0, (a, b) -> a + (a <= b ? b : -b)) ; if (roman.charAt(0) == roman.charAt(1)) { result += 2 * Enum.valueOf(Numeral.class, roman.substring(0, 1)).weight; } return result; } public static void test(long n) { System.out.println(n + " = " + encode(n)); System.out.println(encode(n) + " = " + decode(encode(n))); } public static void main(String[] args) { LongStream.of(1999, 25, 944).forEach(RomanNumerals::test); } }  Output: 1999 = MCMXCIX MCMXCIX = 1999 25 = XXV XXV = 25 944 = CMXLIV CMXLIV = 944 ## JavaScript ### ES5 #### Iteration Translation of: Tcl var roman = { map: [ 1000, 'M', 900, 'CM', 500, 'D', 400, 'CD', 100, 'C', 90, 'XC', 50, 'L', 40, 'XL', 10, 'X', 9, 'IX', 5, 'V', 4, 'IV', 1, 'I', ], int_to_roman: function(n) { var value = ''; for (var idx = 0; n > 0 && idx < this.map.length; idx += 2) { while (n >= this.map[idx]) { value += this.map[idx + 1]; n -= this.map[idx]; } } return value; } } roman.int_to_roman(1999); // "MCMXCIX"  #### Functional composition (function () { 'use strict'; // If the Roman is a string, pass any delimiters through // (Int | String) -> String function romanTranscription(a) { if (typeof a === 'string') { var ps = a.split(/\d+/), dlm = ps.length > 1 ? ps[1] : undefined; return (dlm ? a.split(dlm) .map(function (x) { return Number(x); }) : [a]) .map(roman) .join(dlm); } else return roman(a); } // roman :: Int -> String function roman(n) { return [[1000, "M"], [900, "CM"], [500, "D"], [400, "CD"], [100, "C"], [90, "XC"], [50, "L"], [40, "XL"], [10, "X"], [9, "IX"], [5, "V"], [4, "IV"], [1, "I"]] .reduce(function (a, lstPair) { var m = a.remainder, v = lstPair[0]; return (v > m ? a : { remainder: m % v, roman: a.roman + Array( Math.floor(m / v) + 1 ) .join(lstPair[1]) }); }, { remainder: n, roman: '' }).roman; } // TEST return [2016, 1990, 2008, "14.09.2015", 2000, 1666].map( romanTranscription); })();  Output: ["MMXVI", "MCMXC", "MMVIII", "XIV.IX.MMXV", "MM", "MDCLXVI"]  ### ES6 #### Functional Translation of: Haskell (mapAccumL version) (() => { "use strict"; // -------------- ROMAN INTEGER STRINGS -------------- // roman :: Int -> String const roman = n => mapAccumL(residue => ([k, v]) => second( q => 0 < q ? k.repeat(q) : "" )(remQuot(residue)(v)) )(n)( zip([ "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" ])([ 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 ]) )[1] .join(""); // ---------------------- TEST ----------------------- // main :: IO () const main = () => ( [2016, 1990, 2008, 2000, 2020, 1666].map(roman) ) .join("\n"); // ---------------- GENERIC FUNCTIONS ---------------- // Tuple (,) :: a -> b -> (a, b) const Tuple = a => // A pair of values, possibly of // different types. b => ({ type: "Tuple", "0": a, "1": b, length: 2, *[Symbol.iterator]() { for (const k in this) { if (!isNaN(k)) { yield this[k]; } } } }); // mapAccumL :: (acc -> x -> (acc, y)) -> acc -> // [x] -> (acc, [y]) const mapAccumL = f => // A tuple of an accumulation and a list // obtained by a combined map and fold, // with accumulation from left to right. acc => xs => [...xs].reduce( ([a, bs], x) => second( v => [...bs, v] )( f(a)(x) ), [acc, []] ); // remQuot :: Int -> Int -> (Int, Int) const remQuot = m => n => [m % n, Math.trunc(m / n)]; // second :: (a -> b) -> ((c, a) -> (c, b)) const second = f => // A function over a simple value lifted // to a function over a tuple. // f (a, b) -> (a, f(b)) xy => Tuple( xy[0] )( f(xy[1]) ); // zip :: [a] -> [b] -> [(a, b)] const zip = xs => // The paired members of xs and ys, up to // the length of the shorter of the two lists. ys => Array.from({ length: Math.min(xs.length, ys.length) }, (_, i) => [xs[i], ys[i]]); // MAIN -- return main(); })();  Output: MDCLXVI MCMXC MMVIII MMXVI MMXVIII MMXX #### Declarative function toRoman(num) { return 'I' .repeat(num) .replace(/IIIII/g, 'V') .replace(/VV/g, 'X') .replace(/XXXXX/g, 'L') .replace(/LL/g, 'C') .replace(/CCCCC/g, 'D') .replace(/DD/g, 'M') .replace(/VIIII/g, 'IX') .replace(/LXXXX/g, 'XC') .replace(/XXXX/g, 'XL') .replace(/DCCCC/g, 'CM') .replace(/CCCC/g, 'CD') .replace(/IIII/g, 'IV'); } console.log(toRoman(1666));  Output: MDCLXVI  ## jq Works with: jq Works with gojq, the Go implementation of jq The "easy-to-code" version is presented first, followed by the "orders of magnitude" version. Both versions work for positive integers up to and including 399,999, but note that the Unicode glyphs for 50,000 and 100,000 are not supported in many environments. The test cases and output are identical for both versions and are therefore not repeated. ### Easy-to-code version def to_roman_numeral: def romans: [100000, "\u2188"], [90000, "ↂ\u2188"], [50000, "\u2187"], [40000, "ↂ\u2187"], [10000, "ↂ"], [9000, "Mↂ"], [5000, "ↁ"], [4000, "Mↁ"], [1000, "M"], [900, "CM"], [500, "D"], [400, "CD"], [100, "C"], [90, "XC"], [50, "L"], [40, "XL"], [10, "X"], [9, "IX"], [5, "V"], [4, "IV"], [1, "I"] ; if . < 1 or . > 399999 then "to_roman_numeral: $$.) is out of range" | error else reduce romans as [i, r] ({n: .}; until (.n < i; .res += r | .n = .n - i ) ) | .res end ; Test Cases def testcases: [1668, 1990, 2008, 2020, 4444, 5000, 8999, 39999, 89999, 399999]; "Decimal => Roman:", (testcases[] | " \(.) => \(to_roman_numeral)" ) Output: Decimal => Roman: 1668 => MDCLXVIII 1990 => MCMXC 2008 => MMVIII 2020 => MMXX 4444 => MↁCDXLIV 5000 => ↁ 8999 => ↁMMMCMXCIX 39999 => ↂↂↂMↂCMXCIX 89999 => ↇↂↂↂMↂCMXCIX 399999 => ↈↈↈↂↈMↂCMXCIX  ### "Orders of Magnitude" version Translated from Julia extended to 399,999 def digits: tostring | explode | map( [.]|implode|tonumber); # Non-negative integer to Roman numeral up to 399,999 def to_roman_numeral: if . < 1 or . > 399999 then "to_roman_numeral: \(.) is out of range" | error else [["I", "X", "C", "M", "ↂ", "\u2188"], ["V", "L", "D", "ↁ", "\u2187"]] as DR | (digits|reverse) as digits | reduce range(0;digits|length) as omag ({rnum: ""}; digits[omag] as d | if d == 0 then .omr = "" elif d < 4 then .omr = DR[0][omag] * d elif d == 4 then .omr = DR[0][omag] + DR[1][omag] elif d == 5 then .omr = DR[1][omag] elif d < 9 then .omr = DR[1][omag] + (DR[0][omag] * (d - 5)) else .omr = DR[0][omag] + DR[0][omag+1] end | .rnum = .omr + .rnum ) | .rnum end; ## Jsish This covers both Encode (toRoman) and Decode (fromRoman). /* Roman numerals, in Jsish */ var Roman = { ord: ['M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I'], val: [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1], fromRoman: function(roman:string):number { var n = 0; var re = /IV|IX|I|V|XC|XL|X|L|CD|CM|C|D|M/g; var matches = roman.match(re); if (!matches) return NaN; for (var hit of matches) n += this.val[this.ord.indexOf(hit)]; return n; }, toRoman: function(n:number):string { var roman = ''; var idx = 0; while (n > 0) { while (n >= this.val[idx]) { roman += this.ord[idx]; n -= this.val[idx]; } idx++; } return roman; } }; provide('Roman', 1); if (Interp.conf('unitTest')) { ; Roman.fromRoman('VIII'); ; Roman.fromRoman('MMMDIV'); ; Roman.fromRoman('CDIV'); ; Roman.fromRoman('MDCLXVI'); ; Roman.fromRoman('not'); ; Roman.toRoman(8); ; Roman.toRoman(3504); ; Roman.toRoman(404); ; Roman.toRoman(1666); } /* =!EXPECTSTART!= Roman.fromRoman('VIII') ==> 8 Roman.fromRoman('MMMDIV') ==> 3504 Roman.fromRoman('CDIV') ==> 404 Roman.fromRoman('MDCLXVI') ==> 1666 Roman.fromRoman('not') ==> NaN Roman.toRoman(8) ==> VIII Roman.toRoman(3504) ==> MMMDIV Roman.toRoman(404) ==> CDIV Roman.toRoman(1666) ==> MDCLXVI =!EXPECTEND!= */  Output: prompt jsish -u Roman.jsi [PASS] Roman.jsi ## Julia using Printf function romanencode(n::Integer) if n < 1 || n > 4999 throw(DomainError()) end DR = [["I", "X", "C", "M"] ["V", "L", "D", "MMM"]] rnum = "" for (omag, d) in enumerate(digits(n)) if d == 0 omr = "" elseif d < 4 omr = DR[omag, 1] ^ d elseif d == 4 omr = DR[omag, 1] * DR[omag, 2] elseif d == 5 omr = DR[omag, 2] elseif d < 9 omr = DR[omag, 2] * DR[omag, 1] ^ (d - 5) else omr = DR[omag, 1] * DR[omag + 1, 1] end rnum = omr * rnum end return rnum end testcases = [1990, 2008, 1668] append!(testcases, rand(1:4999, 12)) testcases = unique(testcases) println("Test romanencode, arabic => roman:") for n in testcases @printf("%-4i => %s\n", n, romanencode(n)) end  Output: Test romanencode, arabic => roman: 1990 => MCMXC 2008 => MMVIII 1668 => MDCLXVIII 2928 => MMCMXXVIII 129 => CXXIX 4217 => MMMMCCXVII 1503 => MDIII 2125 => MMCXXV 1489 => MCDLXXXIX 3677 => MMMDCLXXVII 1465 => MCDLXV 1421 => MCDXXI 1642 => MDCXLII 572 => DLXXII 3714 => MMMDCCXIV ## Kotlin val romanNumerals = mapOf( 1000 to "M", 900 to "CM", 500 to "D", 400 to "CD", 100 to "C", 90 to "XC", 50 to "L", 40 to "XL", 10 to "X", 9 to "IX", 5 to "V", 4 to "IV", 1 to "I" ) fun encode(number: Int): String? { if (number > 5000 || number < 1) { return null } var num = number var result = "" for ((multiple, numeral) in romanNumerals.entries) { while (num >= multiple) { num -= multiple result += numeral } } return result } fun main(args: Array<String>) { println(encode(1990)) println(encode(1666)) println(encode(2008)) }  Output: MCMXC MDCLXVI MMVIII  Alternatively: fun Int.toRomanNumeral(): String { fun digit(k: Int, unit: String, five: String, ten: String): String { return when (k) { in 1..3 -> unit.repeat(k) 4 -> unit + five in 5..8 -> five + unit.repeat(k - 5) 9 -> unit + ten else -> throw IllegalArgumentException("k not in range 1..9") } } return when (this) { 0 -> "" in 1..9 -> digit(this, "I", "V", "X") in 10..99 -> digit(this / 10, "X", "L", "C") + (this % 10).toRomanNumeral() in 100..999 -> digit(this / 100, "C", "D", "M") + (this % 100).toRomanNumeral() in 1000..3999 -> "M" + (this - 1000).toRomanNumeral() else -> throw IllegalArgumentException("{this} not in range 0..3999") } }  ## Lasso define br => '\r' // encode roman define encodeRoman(num::integer)::string => { local(ref = array('M'=1000, 'CM'=900, 'D'=500, 'CD'=400, 'C'=100, 'XC'=90, 'L'=50, 'XL'=40, 'X'=10, 'IX'=9, 'V'=5, 'IV'=4, 'I'=1)) local(out = string) with i in #ref do => { while(#num >= #i->second) => { #out->append(#i->first) #num -= #i->second } } return #out } '1990 in roman is '+encodeRoman(1990) br '2008 in roman is '+encodeRoman(2008) br '1666 in roman is '+encodeRoman(1666)  ## LaTeX The macro \Roman is defined for uppercase roman numeral, accepting as argument a name of an existing counter. \documentclass{minimal} \newcounter{currentyear} \setcounter{currentyear}{\year} \begin{document} Anno Domini \Roman{currentyear} \end{document}  ## LiveCode function toRoman intNum local roman,numArabic put "M,CM,D,CD,C,XC,L,XL,X,IX,V,IV,I" into romans put "1000,900,500,400,100,90,50,40,10,9,5,4,1" into arabics put intNum into numArabic repeat with n = 1 to the number of items of romans put numArabic div item n of arabics into nums if nums > 0 then put repeatChar(item n of romans,nums) after roman add -(nums * item n of arabics) to numArabic end if end repeat return roman end toRoman function repeatChar c n local cc repeat n times put c after cc end repeat return cc end repeatChar Examples toRoman(2009) -- MMIX toRoman(1666) -- MDCLXVI toRoman(1984) -- MCMLXXXIV toRoman(3888) -- MMMDCCCLXXXVIII ## Logo make "roman.rules [ [1000 M] [900 CM] [500 D] [400 CD] [ 100 C] [ 90 XC] [ 50 L] [ 40 XL] [ 10 X] [ 9 IX] [ 5 V] [ 4 IV] [ 1 I] ] to roman :n [:rules :roman.rules] [:acc "||] if empty? :rules [output :acc] if :n < first first :rules [output (roman :n bf :rules :acc)] output (roman :n - first first :rules :rules word :acc last first :rules) end Works with: UCB Logo make "patterns [[?] [? ?] [? ? ?] [? ?2] [?2] [?2 ?] [?2 ? ?] [?2 ? ? ?] [? ?3]] to digit :d :numerals if :d = 0 [output "||] output apply (sentence "\( "word (item :d :patterns) "$$) :numerals end to digits :n :numerals output word ifelse :n < 10 ["||] [digits int :n/10 bf bf :numerals] ~ digit modulo :n 10 :numerals end to roman :n if or :n < 0 :n >= 4000 [output [EX MODVS!]] output digits :n [I V X L C D M] end print roman 1999 ; MCMXCIX print roman 25 ; XXV print roman 944 ; CMXLIV ## LOLCODE HAI 1.2 I HAS A Romunz ITZ A BUKKIT Romunz HAS A SRS 0 ITZ "M" Romunz HAS A SRS 1 ITZ "CM" Romunz HAS A SRS 2 ITZ "D" Romunz HAS A SRS 3 ITZ "CD" Romunz HAS A SRS 4 ITZ "C" Romunz HAS A SRS 5 ITZ "XC" Romunz HAS A SRS 6 ITZ "L" Romunz HAS A SRS 7 ITZ "XL" Romunz HAS A SRS 8 ITZ "X" Romunz HAS A SRS 9 ITZ "IX" Romunz HAS A SRS 10 ITZ "V" Romunz HAS A SRS 11 ITZ "IV" Romunz HAS A SRS 12 ITZ "I" I HAS A Valuez ITZ A BUKKIT Valuez HAS A SRS 0 ITZ 1000 Valuez HAS A SRS 1 ITZ 900 Valuez HAS A SRS 2 ITZ 500 Valuez HAS A SRS 3 ITZ 400 Valuez HAS A SRS 4 ITZ 100 Valuez HAS A SRS 5 ITZ 90 Valuez HAS A SRS 6 ITZ 50 Valuez HAS A SRS 7 ITZ 40 Valuez HAS A SRS 8 ITZ 10 Valuez HAS A SRS 9 ITZ 9 Valuez HAS A SRS 10 ITZ 5 Valuez HAS A SRS 11 ITZ 4 Valuez HAS A SRS 12 ITZ 1 HOW IZ I Romunize YR Num I HAS A Result ITZ "" IM IN YR Outer UPPIN YR Dummy TIL BOTH SAEM Num AN 0 IM IN YR Inner UPPIN YR Index TIL BOTH SAEM Index AN 13 BOTH SAEM Num AN BIGGR OF Num AN Valuez'Z SRS Index, O RLY? YA RLY Num R DIFF OF Num AN Valuez'Z SRS Index Result R SMOOSH Result Romunz'Z SRS Index MKAY GTFO OIC IM OUTTA YR Inner IM OUTTA YR Outer FOUND YR Result IF U SAY SO VISIBLE SMOOSH 2009 " = " I IZ Romunize YR 2009 MKAY MKAY VISIBLE SMOOSH 1666 " = " I IZ Romunize YR 1666 MKAY MKAY VISIBLE SMOOSH 3888 " = " I IZ Romunize YR 3888 MKAY MKAY KTHXBYE Output: 2009 = MMIX 1666 = MDCLXVI 3888 = MMMDCCCLXXXVIII ## LotusScript Function toRoman(value) As String Dim arabic(12) As Integer Dim roman(12) As String arabic(0) = 1000 arabic(1) = 900 arabic(2) = 500 arabic(3) = 400 arabic(4) = 100 arabic(5) = 90 arabic(6) = 50 arabic(7) = 40 arabic(8) = 10 arabic(9) = 9 arabic(10) = 5 arabic(11) = 4 arabic(12) = 1 roman(0) = "M" roman(1) = "CM" roman(2) = "D" roman(3) = "CD" roman(4) = "C" roman(5) = "XC" roman(6) = "L" roman(7) = "XL" roman(8) = "X" roman(9) = "IX" roman(10) = "V" roman(11) = "IV" roman(12) = "I" Dim i As Integer, result As String For i = 0 To 12 Do While value >= arabic(i) result = result + roman(i) value = value - arabic(i) Loop Next i toRoman = result End Function ## Lua romans = { {1000, "M"}, {900, "CM"}, {500, "D"}, {400, "CD"}, {100, "C"}, {90, "XC"}, {50, "L"}, {40, "XL"}, {10, "X"}, {9, "IX"}, {5, "V"}, {4, "IV"}, {1, "I"} } k = io.read() + 0 for _, v in ipairs(romans) do --note that this is -not- ipairs. val, let = unpack(v) while k >= val do k = k - val io.write(let) end end print()  ## M4 define(roman',ifelse(eval($1>=1000),1,M'roman(eval($1-1000))', ifelse(eval($1>=900),1,CM'roman(eval($1-900))', ifelse(eval($1>=500),1,D'roman(eval($1-500))', ifelse(eval($1>=100),1,C'roman(eval($1-100))', ifelse(eval($1>=90),1,XC'roman(eval($1-90))', ifelse(eval($1>=50),1,L'roman(eval($1-50))', ifelse(eval($1>=40),1,XL'roman(eval($1-40))', ifelse(eval($1>=10),1,X'roman(eval($1-10))', ifelse(eval($1>=9),1,IX'roman(eval($1-9))', ifelse(eval($1>=5),1,V'roman(eval($1-5))', ifelse(eval($1>=4),1,IV'roman(eval($1-4))', ifelse(eval($1>=1),1,I'roman(eval($1-1))' )')')')')')')')')')')')')dnl dnl roman(3675) Output: MMMDCLXXV  ## Maple > for n in [ 1666, 1990, 2008 ] do printf( "%d\t%s\n", n, convert( n, 'roman' ) ) end: 1666 MDCLXVI 1990 MCMXC 2008 MMVIII ## Mathematica /Wolfram Language RomanNumeral is a built-in function in the Wolfram language. Examples: RomanNumeral[4] RomanNumeral[99] RomanNumeral[1337] RomanNumeral[1666] RomanNumeral[6889]  gives back: IV XCIX MCCCXXXVII MDCLXVI MMMMMMDCCCLXXXIX ## Mercury The non-ceremonial work in this program starts at the function to_roman/1. Unusually for Mercury the function is semi-deterministic. This is because some of the helper functions it calls are also semi-deterministic and the determinism subsystem propagates the status upward. (There are ways to stop it from doing this, but it would distract from the actual Roman numeral conversion process so the semi-determinism has been left in.) to_roman/1 is just a string of chained function calls. The number is passed in as a string (and the main/2 predicate ensures that it is *only* digits!) is converted into a list of characters. This list is then reversed and the Roman numeral version is built from it. This resulting character list is then converted back into a string and returned. build_roman/1 takes the lead character off the list (reversed numerals) and then recursively calls itself. It uses the promote/2 predicate to multiply the ensuing Roman numerals (if any) by an order of magnitude and converts the single remaining digit to the appropriate list of Roman numerals. To clarify, if it's passed the number "123" (encoded by this point as ['3', '2', '1']) the following transpires: • The '3' is removed and build_roman/1 is now called with ['2', '1']. • The '2' is removed and the function is recursively called with ['1']. • The '1' is removed and the function is recursively called with [] (the empty list).. • The function returns []. • The [] has its (non-existent) digits promoted and then gets ['I'] appended (1 converts to ['I'] via digit_to_roman/1). • The ['I'] has its (single) digit promoted and is converted to ['X'] and then gets ['I','I'] appended from the 2's conversion. The resulting list is now ['X','I','I'] (or 12). • The ['X','I','I'] has all of its digits promoted, yielding ['C','X','X'] before getting ['I','I','I'] appended. The resulting list is now ['C','X','X','I','I','I'] which is converted into the string "CXXIII" back up in to_roman/1. It is possible for this to be implemented differently even keeping the same algorithm. For example the map module from the standard library could be used for looking up conversions and promotions instead of having digit_to_roman/1 and promote. This would require, however, either passing around the conversion tables constantly (bulking up the parameter lists of all functions and predicates) or creating said conversion tables each time at point of use (slowing down the implementation greatly). Now the semi-determinism of the functions involved is a little bit of a problem. In the main/2 predicate you can see one means of dealing with it. main/2 *must* be deterministic (or cc_multi, but this is equivalent for this discussion). There can be *no* failure in a called function or predicate … unless that failure is explicitly handled somehow. In this implementation the failure is handled in the foldl/4's provided higher-order predicate lambda. The call to to_roman/1 is called within a conditional and both the success (true) and failure (false) branches are handled. This makes the passed-in predicate lambda deterministic, even though the implementation functions and predicates are semi-deterministic. But why are they semi-deterministic? Well, this has to do with the type system. It doesn't permit sub-typing, so when the type of a predicate is, say pred(char, char) (as is the case for promote/2), the underlying implementation *must* handle *all* values that a type char could possibly hold. It is trivial to see that our code does not. This means that, in theory, it is possible that promote/2 (or digit_to_roman/1) could be passed a value which cannot be processed, thus triggering a false result, and thus being semi-deterministic. ### roman.m :- module roman. :- interface. :- import_module io. :- pred main(io::di, io::uo) is det. :- implementation. :- import_module char, int, list, string. main(!IO) :- command_line_arguments(Args, !IO), filter(is_all_digits, Args, CleanArgs), foldl((pred(Arg::in, !.IO::di, !:IO::uo) is det :- ( Roman = to_roman(Arg) -> format("%s => %s", [s(Arg), s(Roman)], !IO), nl(!IO) ; format("%s cannot be converted.", [s(Arg)], !IO), nl(!IO) ) ), CleanArgs, !IO). :- func to_roman(string::in) = (string::out) is semidet. to_roman(Number) = from_char_list(build_roman(reverse(to_char_list(Number)))). :- func build_roman(list(char)) = list(char). :- mode build_roman(in) = out is semidet. build_roman([]) = []. build_roman([D|R]) = Roman :- map(promote, build_roman(R), Interim), Roman = Interim ++ digit_to_roman(D). :- func digit_to_roman(char) = list(char). :- mode digit_to_roman(in) = out is semidet. digit_to_roman('0') = []. digit_to_roman('1') = ['I']. digit_to_roman('2') = ['I','I']. digit_to_roman('3') = ['I','I','I']. digit_to_roman('4') = ['I','V']. digit_to_roman('5') = ['V']. digit_to_roman('6') = ['V','I']. digit_to_roman('7') = ['V','I','I']. digit_to_roman('8') = ['V','I','I','I']. digit_to_roman('9') = ['I','X']. :- pred promote(char::in, char::out) is semidet. promote('I', 'X'). promote('V', 'L'). promote('X', 'C'). promote('L', 'D'). promote('C', 'M'). :- end_module roman. Output: $ '''mmc roman && ./roman 1 8 27 64 125 216 343 512 729 1000 1331 1728 2197 2744 3375'''
''1 => I''
''8 => VIII''
''27 => XXVII''
''64 => LXIV''
''125 => CXXV''
''216 => CCXVI''
''343 => CCCXLIII''
''512 => DXII''
''729 => DCCXXIX''
''1000 => M''
''1331 => MCCCXXXI''
''1728 => MDCCXXVIII''
''2197 => MMCXCVII''
''2744 => MMDCCXLIV''
''3375 => MMMCCCLXXV''


### roman2.m

Another implementation using an algorithm inspired by the Erlang implementation could look like this:

:- module roman2.

:- interface.

:- import_module io.

:- pred main(io::di, io::uo) is det.

:- implementation.

:- import_module char, int, list, string.

main(!IO) :-
command_line_arguments(Args, !IO),
filter_map(to_int, Args, CleanArgs),
foldl((pred(Arg::in, !.IO::di, !:IO::uo) is det :-
( Roman = to_roman(Arg) ->
format("%i => %s",
[i(Arg), s(from_char_list(Roman))], !IO),
nl(!IO)
;     format("%i cannot be converted.", [i(Arg)], !IO), nl(!IO) )
), CleanArgs, !IO).

:- func to_roman(int) = list(char).
:- mode to_roman(in)  = out is semidet.
to_roman(N) = ( N >= 1000 ->
['M'] ++ to_roman(N - 1000)
;( N >= 100 ->
digit(N / 100, 'C', 'D', 'M') ++ to_roman(N rem 100)
;( N >= 10 ->
digit(N / 10, 'X', 'L', 'C') ++ to_roman(N rem 10)
;( N >= 1 ->
digit(N, 'I', 'V', 'X')
; [] ) ) ) ).

:- func digit(int, char, char, char) = list(char).
:- mode digit(in,  in,   in,   in)   = out is semidet.
digit(1, X, _, _) = [X].
digit(2, X, _, _) = [X, X].
digit(3, X, _, _) = [X, X, X].
digit(4, X, Y, _) = [X, Y].
digit(5, _, Y, _) = [Y].
digit(6, X, Y, _) = [Y, X].
digit(7, X, Y, _) = [Y, X, X].
digit(8, X, Y, _) = [Y, X, X, X].
digit(9, X, _, Z) = [X, Z].

:- end_module roman2.

This implementation calculates the value of the thousands, then the hundreds, then the tens, then the ones. In each case it uses the digit/4 function and some tricks with unification to build the appropriate list of characters for the digit and multiplier being targeted.

Its output is identical to that of the previous version.

## Miranda

main :: [sys_message]
main = [ Stdout (show n ++ ": " ++ toroman n ++ "\n")
| n <- [1990, 2008, 1666, 2023]]

toroman :: num->[char]
toroman 0 = ""
toroman n = d ++ toroman (n - v)
where digits = [("M",1000),("CM",900),("D",500),("CD",400),
("C",100),("XC",90),("L",50),("XL",40),
("X",10),("IX",9),("V",5),("IV",4),
("I",1)]
(d, v) = hd [(d,v) | (d,v) <- digits; v <= n]
Output:
1990: MCMXC
2008: MMVIII
1666: MDCLXVI
2023: MMXXIII

## Modula-2

Translation of: DWScript
Works with: ADW Modula-2 version any (Compile with the linker option Console Application).
MODULE RomanNumeralsEncode;

FROM Strings IMPORT
Append;
FROM STextIO IMPORT
WriteString, WriteLn;

CONST
MaxChars = 15;
(* 3888 or MMMDCCCLXXXVIII (15 chars) is the longest string properly encoded
with these symbols. *)

TYPE
TRomanNumeral = ARRAY [0 .. MaxChars - 1] OF CHAR;

PROCEDURE ToRoman(AValue: CARDINAL; VAR OUT Destination: ARRAY OF CHAR);
TYPE
TRomanSymbols = ARRAY [0 .. 1] OF CHAR;
TWeights = ARRAY [0 .. 12] OF CARDINAL;
TSymbols = ARRAY [0 .. 12] OF TRomanSymbols;
CONST
Weights = TWeights {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
Symbols = TSymbols {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX",
"V", "IV", "I"};
VAR
I: CARDINAL;
BEGIN
Destination := "";
I := 0;
WHILE (I <= HIGH(Weights)) AND (AValue > 0) DO
WHILE AValue >= Weights[I] DO
Append(Symbols[I], Destination);
AValue := AValue - Weights[I]
END;
INC(I);
END;
END ToRoman;

VAR
Numeral: TRomanNumeral;

BEGIN
ToRoman(1990, Numeral); WriteString(Numeral); WriteLn; (* MCMXC *)
ToRoman(2018, Numeral); WriteString(Numeral); WriteLn; (* MMXVIII *)
ToRoman(3888, Numeral); WriteString(Numeral); WriteLn; (* MMMDCCCLXXXVIII *)
END RomanNumeralsEncode.

Output:
MCMXC
MMXVIII
MMMDCCCLXXXVIII


## MUMPS

TOROMAN(INPUT)
;Converts INPUT into a Roman numeral. INPUT must be an integer between 1 and 3999
;OUTPUT is the string to return
;I is a loop variable
;CURRVAL is the current value in the loop
QUIT:($FIND(INPUT,".")>1)!(INPUT<=0)!(INPUT>3999) "Invalid input" NEW OUTPUT,I,CURRVAL SET OUTPUT="",CURRVAL=INPUT SET:$DATA(ROMANNUM)=0 ROMANNUM="I^IV^V^IX^X^XL^L^XC^C^CD^D^CM^M"
SET:$DATA(ROMANVAL)=0 ROMANVAL="1^4^5^9^10^40^50^90^100^400^500^900^1000" FOR I=$LENGTH(ROMANVAL,"^"):-1:1 DO
.FOR  Q:CURRVAL<$PIECE(ROMANVAL,"^",I) SET OUTPUT=OUTPUT_$PIECE(ROMANNUM,"^",I),CURRVAL=CURRVAL-PIECE(ROMANVAL,"^",I) KILL I,CURRVAL QUIT OUTPUT Output: USER>W $$ROMAN^ROSETTA(1666) MDCLXVI USER>W$$TOROMAN^ROSETTA(2010) MMX USER>W $$TOROMAN^ROSETTA(949) CMXLIX USER>W$$TOROMAN^ROSETTA(949.24) Invalid input USER>W TOROMAN^ROSETTA(-949) Invalid input Another variant TOROMAN(n) ;return empty string if input parameter 'n' is not in 1-3999 Quit:(n'?1.4N)!(n'<4000)!'n "" New r Set r="" New p Set p=Length(n) New j,x For j=1:1:p Do . Set x=Piece("~I~II~III~IV~V~VI~VII~VIII~IX","~",Extract(n,j)+1) . Set x=Translate(x,"IVX",Piece("IVX~XLC~CDM~M","~",p-j+1)) . Set r=r_x Quit r ## Nim Translation of: Python import strutils const nums = [(1000, "M"), (900, "CM"), (500, "D"), (400, "CD"), (100, "C"), (90, "XC"), (50, "L"), (40, "XL"), (10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I")] proc toRoman(n: Positive): string = var n = n.int for (a, r) in nums: result.add(repeat(r, n div a)) n = n mod a for i in [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 40, 50, 60, 69, 70, 80, 90, 99, 100, 200, 300, 400, 500, 600, 666, 700, 800, 900, 1000, 1009, 1444, 1666, 1945, 1997, 1999, 2000, 2008, 2010, 2011, 2500, 3000, 3999]: echo (i).align(4), ": ", i.toRoman  Output:  1: I 2: II 3: III 4: IV 5: V 6: VI 7: VII 8: VIII 9: IX 10: X 11: XI 12: XII 13: XIII 14: XIV 15: XV 16: XVI 17: XVII 18: XVIII 19: XIX 20: XX 25: XXV 30: XXX 40: XL 50: L 60: LX 69: LXIX 70: LXX 80: LXXX 90: XC 99: XCIX 100: C 200: CC 300: CCC 400: CD 500: D 600: DC 666: DCLXVI 700: DCC 800: DCCC 900: CM 1000: M 1009: MIX 1444: MCDXLIV 1666: MDCLXVI 1945: MCMXLV 1997: MCMXCVII 1999: MCMXCIX 2000: MM 2008: MMVIII 2010: MMX 2011: MMXI 2500: MMD 3000: MMM 3999: MMMCMXCIX ## Objeck Translation of: C sharp bundle Default { class Roman { nums: static : Int[]; rum : static : String[]; function : Init() ~ Nil { nums := [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]; rum := ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"]; } function : native : ToRoman(number : Int) ~ String { result := ""; for(i :=0; i < nums->Size(); i += 1;) { while(number >= nums[i]) { result->Append(rum[i]); number -= nums[i]; }; }; return result; } function : Main(args : String[]) ~ Nil { Init(); ToRoman(1999)->PrintLine(); ToRoman(25)->PrintLine(); ToRoman(944)->PrintLine(); } } } ## OCaml With an explicit decimal digit representation list: let digit x y z = function 1 -> [x] | 2 -> [x;x] | 3 -> [x;x;x] | 4 -> [x;y] | 5 -> [y] | 6 -> [y;x] | 7 -> [y;x;x] | 8 -> [y;x;x;x] | 9 -> [x;z] let rec to_roman x = if x = 0 then [] else if x < 0 then invalid_arg "Negative roman numeral" else if x >= 1000 then 'M' :: to_roman (x - 1000) else if x >= 100 then digit 'C' 'D' 'M' (x / 100) @ to_roman (x mod 100) else if x >= 10 then digit 'X' 'L' 'C' (x / 10) @ to_roman (x mod 10) else digit 'I' 'V' 'X' x Output: # to_roman 1999;; - : char list = ['M'; 'C'; 'M'; 'X'; 'C'; 'I'; 'X'] # to_roman 25;; - : char list = ['X'; 'X'; 'V'] # to_roman 944;; - : char list = ['C'; 'M'; 'X'; 'L'; 'I'; 'V']  ## Oforth [ [1000,"M"], [900,"CM"], [500,"D"], [400,"CD"], [100,"C"], [90,"XC"], [50,"L"], [40,"XL"], [10,"X"], [9,"IX"], [5,"V"], [4,"IV"], [1,"I"] ] const: Romans : roman(n) | r | StringBuffer new Romans forEach: r [ while(r first n <=) [ r second << n r first - ->n ] ] ; ## OpenEdge/Progress FUNCTION encodeRoman RETURNS CHAR ( i_i AS INT ): DEF VAR cresult AS CHAR. DEF VAR croman AS CHAR EXTENT 7 INIT [ "M", "D", "C", "L", "X", "V", "I" ]. DEF VAR idecimal AS INT EXTENT 7 INIT [ 1000, 500, 100, 50, 10, 5, 1 ]. DEF VAR ipos AS INT INIT 1. DO WHILE i_i > 0: IF i_i - idecimal[ ipos ] >= 0 THEN ASSIGN cresult = cresult + croman[ ipos ] i_i = i_i - idecimal[ ipos ] . ELSE IF ipos < EXTENT( croman ) - 1 AND i_i - ( idecimal[ ipos ] - idecimal[ ipos + 2 ] ) >= 0 THEN ASSIGN cresult = cresult + croman[ ipos + 2 ] + croman[ ipos ] i_i = i_i - ( idecimal[ ipos ] - idecimal[ ipos + 2 ] ) ipos = ipos + 1 . ELSE ipos = ipos + 1. END. RETURN cresult. END FUNCTION. /* encodeRoman */ MESSAGE 1990 encodeRoman( 1990 ) SKIP 2008 encodeRoman( 2008 ) SKIP 2000 encodeRoman( 2000 ) SKIP 1666 encodeRoman( 1666 ) SKIP VIEW-AS ALERT-BOX. Output: --------------------------- Message (Press HELP to view stack trace) --------------------------- 1990 MCMXC 2008 MMVIII 2000 MM 1666 MDCLXVI --------------------------- OK Help --------------------------- ## Oz Translation of: Haskell declare fun {Digit X Y Z K} unit([X] [X X] [X X X] [X Y] [Y] [Y X] [Y X X] [Y X X X] [X Z]) .K end fun {ToRoman X} if X == 0 then "" elseif X < 0 then raise toRoman(negativeInput X) end elseif X >= 1000 then "M"#{ToRoman X-1000} elseif X >= 100 then {Digit &C &D &M X div 100}#{ToRoman X mod 100} elseif X >= 10 then {Digit &X &L &C X div 10}#{ToRoman X mod 10} else {Digit &I &V &X X} end end in {ForAll {Map [1999 25 944] ToRoman} System.showInfo} ## PARI/GP Old-style Roman numerals oldRoman(n)={ while(n>999999, n-=1000000; print1("((((I))))") ); if(n>499999, n-=500000; print1("I))))") ); while(n>99999, n-=100000; print1("(((I)))") ); if(n>49999, n-=50000; print1("I)))") ); while(n>9999, n-=10000; print1("((I))") ); if(n>4999, n-=5000; print1("I))") ); while(n>999, n-=1000; print1("(I)") ); if(n>499, n-=500; print1("I)") ); while(n>99, n-=100; print1("C") ); if(n>49, n-=50; print1("L"); ); while(n>9, n-=10; print1("X") ); if(n>4, n-=5; print1("V"); ); while(n, n--; print1("I") ); print() }; This simple version of medieval Roman numerals does not handle large numbers. medievalRoman(n)={ while(n>999, n-=1000; print1("M") ); if(n>899, n-=900; print1("CM") ); if(n>499, n-=500; print1("D") ); if(n>399, n-=400; print1("CD") ); while(n>99, n-=100; print1("C") ); if(n>89, n-=90; print1("XC") ); if(n>49, n-=50; print1("L") ); if(n>39, n-=40; print1("XL") ); while(n>9, n-=10; print1("X") ); if(n>8, n-=9; print1("IX") ); if(n>4, n-=5; print1("V") ); if(n>3, n-=4; print1("IV") ); while(n, n--; print1("I") ); print() }; ## Pascal See Delphi ## PascalABC.NET var anums := |1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1|; var rnums := 'M CM D CD C XC L XL X IX V IV I'.split; function ToRoman(x: integer): string; begin Result := ''; foreach var (a,r) in anums.Zip(rnums) do begin var n := x div a; x := x mod a; Result += r * n; end; end; begin var test := |1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 40, 50, 60, 69, 70, 80, 90, 99, 100, 200, 300, 400, 500, 600, 666, 700, 800, 900, 1000, 1009, 1444, 1666, 1945, 1997, 1999, 2000, 2008, 2010, 2011, 2500, 3000, 3999|; foreach var x in test do Println('{x} - {ToRoman(x)}') end. Output: 1666 - MDCLXVI 1945 - MCMXLV 1997 - MCMXCVII 1999 - MCMXCIX 2000 - MM 2008 - MMVIII 2010 - MMX 2011 - MMXI 2500 - MMD 3000 - MMM 3999 - MMMCMXCIX  ## Peloton Roman numbers are built in to Peloton as a particular form of national number. However, for the sake of the task the _RO opcode has been defined. <@ DEFUDOLITLIT>_RO|__Transformer|<@ DEFKEYPAR>__NationalNumericID|2</@><@ LETRESCS%NNMPAR>...|1</@></@> <@ ENUDLSTLITLIT>1990,2008,1,2,64,124,1666,10001|,| <@ SAYELTLST>...</@> is <@ SAY_ROELTLSTLIT>...|RomanLowerUnicode</@> <@ SAY_ROELTLSTLIT>...|RomanUpperUnicode</@> <@ SAY_ROELTLSTLIT>...|RomanASCII</@> </@> Same code in padded-out, variable-length English dialect <# DEFINE USERDEFINEDOPCODE LITERAL LITERAL>_RO|__Transformer|<# DEFINE KEYWORD PARAMETER>__NationalNumericID|2</#><# LET RESULT CAST NATIONALNUMBER PARAMETER>...|1</#></#> <# ENUMERATION LAMBDASPECIFIEDDELMITER LIST LITERAL LITERAL>1990,2008,1,2,64,124,1666,10001|,| <# SAY ELEMENT LIST>...</#> is <# SAY _RO ELEMENT LIST LITERAL>...|RomanLowerUnicode</#> <# SAY _RO ELEMENT LIST LITERAL>...|RomanUpperUnicode</#> <# SAY _RO ELEMENT LIST LITERAL>...|RomanASCII</#> </#> Output: Notice here the three different ways of representing the results. For reasons for notational differences, see wp:Roman_numerals#Alternate_forms 1990 is ⅿⅽⅿⅹⅽ ⅯⅭⅯⅩⅭ MCMXC 2008 is ⅿⅿⅷ ⅯⅯⅧ MMVIII 1 is ⅰ Ⅰ I 2 is ⅱ Ⅱ II 64 is ⅼⅹⅳ ⅬⅩⅣ LXIV 124 is ⅽⅹⅹⅳ ⅭⅩⅩⅣ CXXIV 1666 is ⅿⅾⅽⅼⅹⅵ ⅯⅮⅭⅬⅩⅥ MDCLXVI 10001 is ⅿⅿⅿⅿⅿⅿⅿⅿⅿⅿⅰ ↂⅠ MMMMMMMMMMI ## Perl #### Simple program Simple, fast, produces same output as the Math::Roman module and the Raku example, less crazy than writing a Latin program, and doesn't require experimental modules like the Raku translation. my @symbols = ( [1000, 'M'], [900, 'CM'], [500, 'D'], [400, 'CD'], [100, 'C'], [90, 'XC'], [50, 'L'], [40, 'XL'], [10, 'X'], [9, 'IX'], [5, 'V'], [4, 'IV'], [1, 'I'] ); sub roman { my(n, $r) = (shift, ''); ($r, $n) = ('-', -$n) if $n < 0; # Optional handling of negative input foreach my$s (@symbols) {
my($arabic,$roman) = @$s; ($r, $n) = ($r .= $roman x int($n/$arabic),$n % $arabic) if$n >= $arabic; }$r;
}

#### Ported version of Raku

use List::MoreUtils qw( natatime );

my %symbols = (
1 => "I", 5 => "V", 10 => "X", 50 => "L", 100 => "C",
500 => "D", 1_000 => "M"
);

my @subtractors = (
1_000, 100,  500, 100,  100, 10,  50, 10,  10, 1,  5, 1,  1, 0
);

sub roman {
return '' if 0 == (my $n = shift); my$iter = natatime 2, @subtractors;
while( my ($cut,$minus) = $iter->() ) {$n >= $cut and return$symbols{$cut} . roman($n - $cut);$n >= $cut -$minus
and return $symbols{$minus} . roman($n +$minus);
}
};

print roman($_) . "\n" for 1..2012; ## Phix with javascript_semantics function toRoman(integer v) sequence roman = {"M", "CM", "D","CD", "C","XC","L","XL","X","IX","V","IV","I"}, decml = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 } string res = "" integer val = v for i=1 to length(roman) do while val>=decml[i] do res &= roman[i] val -= decml[i] end while end for return {v,res} -- (for output) end function ?apply({1990,2008,1666},toRoman) Output: {{1990,"MCMXC"},{2008,"MMVIII"},{1666,"MDCLXVI"}}  ### cheating slightly with javascript_semantics requires("1.0.5") function toRoman(integer n) return {n,sprintf("%R",n)} end function same output (builtins\VM\pprntfN.e/toRoman() is somewhat more obfuscated and faster than the above) ## Phixmonti include ..\Utilitys.pmt def romanEnc /# n -- s #/ var number "" var res ( ( 1000 "M" ) ( 900 "CM" ) ( 500 "D" ) ( 400 "CD" ) ( 100 "C" ) ( 90 "XC" ) ( 50 "L" ) ( 40 "XL" ) ( 10 "X" ) ( 9 "IX" ) ( 5 "V" ) ( 4 "IV" ) ( 1 "I" ) ) len for get 1 get number over / int number rot mod var number swap 2 get rot dup if for drop res over chain var res endfor else drop endif drop drop endfor drop res enddef 1968 romanEnc print Translation of: Lua def romanEnc /# n -- s #/ var k ( ( 1000 "M" ) ( 900 "CM" ) ( 500 "D" ) ( 400 "CD" ) ( 100 "C" ) ( 90 "XC" ) ( 50 "L" ) ( 40 "XL" ) ( 10 "X" ) ( 9 "IX" ) ( 5 "V" ) ( 4 "IV" ) ( 1 "I" ) ) len for get 2 get var let 1 get var val drop k val >= while k val - var k let print k val >= endwhile endfor drop nl enddef 1968 romanEnc Without vars def romanEnc /# n -- s #/ >ps ( ( 1000 "M" ) ( 900 "CM" ) ( 500 "D" ) ( 400 "CD" ) ( 100 "C" ) ( 90 "XC" ) ( 50 "L" ) ( 40 "XL" ) ( 10 "X" ) ( 9 "IX" ) ( 5 "V" ) ( 4 "IV" ) ( 1 "I" ) ) len for get 2 get swap 1 get nip tps over >= while ps> over - >ps over print tps over >= endwhile drop drop endfor ps> drop drop nl enddef 1968 romanEnc ## PHP Works with: PHP version 4+ tested in 5.2.12 /** * int2roman * Convert any positive value of a 32-bit signed integer to its modern roman * numeral representation. Numerals within parentheses are multiplied by * 1000. ie. M == 1 000, (M) == 1 000 000, ((M)) == 1 000 000 000 * * @param number - an integer between 1 and 2147483647 * @return roman numeral representation of number */ function int2roman($number)
{
if (!is_int($number) ||$number < 1) return false; // ignore negative numbers and zero

$integers = array(900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1);$numerals = array('CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I');
$major = intval($number / 1000) * 1000;
$minor =$number - $major;$numeral = $leastSig = ''; for ($i = 0; $i < sizeof($integers); $i++) { while ($minor >= $integers[$i]) {
$leastSig .=$numerals[$i];$minor  -= $integers[$i];
}
}

if ($number >= 1000 &&$number < 40000) {
if ($major >= 10000) {$numeral .= '(';
while ($major >= 10000) {$numeral .= 'X';
$major -= 10000; }$numeral .= ')';
}
if ($major == 9000) {$numeral .= 'M(X)';
return $numeral .$leastSig;
}
if ($major == 4000) {$numeral .= 'M(V)';
return $numeral .$leastSig;
}
if ($major >= 5000) {$numeral .= '(V)';
$major -= 5000; } while ($major >= 1000) {
$numeral .= 'M';$major -= 1000;
}
}

if ($number >= 40000) {$major = $major/1000;$numeral .= '(' . int2roman($major) . ')'; } return$numeral . $leastSig; } ## Picat go => List = [455,999,1990,1999,2000,2001,2008,2009,2010,2011,2012,1666,3456,3888,4000], foreach(Val in List) printf("%4d: %w\n", Val, roman_encode(Val)) end, nl. roman_encode(Val) = Res => if Val <= 0 then Res := -1 else Arabic = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1], Roman = ["M", "CM", "D", "CD", "C", "XC","L","XL","X","IX","V","IV","I"], Res = "", foreach(I in 1..Arabic.length) while(Val >= Arabic[I]) Res := Res ++ Roman[I], Val := Val - Arabic[I] end end end. Output:  455: CDLV 999: CMXCIX 1990: MCMXC 1999: MCMXCIX 2000: MM 2001: MMI 2008: MMVIII 2009: MMIX 2010: MMX 2011: MMXI 2012: MMXII 1666: MDCLXVI 3456: MMMCDLVI 3888: MMMDCCCLXXXVIII 4000: MMMM ### Longest numeral Which number encodes to the longest Roman numerals in the interval 1..4000: go2 => All = [Len=I=roman_encode(I) : I in 1..4000,E=roman_encode(I), Len=E.len].sort_down, println(All[1..2]), nl. Output: [15 = 3888 = MMMDCCCLXXXVIII,14 = 3887 = MMMDCCCLXXXVII] ## PicoLisp (de roman (N) (pack (make (mapc '((C D) (while (>= N D) (dec 'N D) (link C) ) ) '(M CM D CD C XC L XL X IX V IV I) (1000 900 500 400 100 90 50 40 10 9 5 4 1) ) ) ) ) Output: : (roman 1009) -> "MIX" : (roman 1666) -> "MDCLXVI" ## Pike import String; int main(){ write(int2roman(2009) + "\n"); write(int2roman(1666) + "\n"); write(int2roman(1337) + "\n"); } ## PL/I /* From Wiki Fortran */ roman: procedure (n) returns(character (32) varying); declare n fixed binary nonassignable; declare (d, m) fixed binary; declare (r, m_div) character (32) varying; declare d_dec(13) fixed binary static initial (1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1); declare d_rom(13) character (2) varying static initial ('M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I'); r = ''; m = n; do d = 1 to 13; m_div = m / d_dec (d); r = r || copy (d_rom (d), m_div); m = m - d_dec (d) * m_div; end; return (r); end roman; Results:  11 XI 1990 MCMXC 2008 MMVIII 1666 MDCLXVI 1999 MCMXCIX  ## PL/SQL /***************************************************************** *$Author: Atanas Kebedjiev $***************************************************************** * Encoding an Arabic numeral to a Roman in the range 1..3999 is much simpler as Oracle provides the conversion formats. * Please see also the SQL solution for the same task. */ CREATE OR REPLACE FUNCTION rencode(an IN NUMBER) RETURN VARCHAR2 IS BEGIN RETURN to_char(an, 'RN'); END rencode; BEGIN DBMS_OUTPUT.PUT_LINE ('2012 = ' || rencode('2012')); -- MMXII DBMS_OUTPUT.PUT_LINE ('1951 = ' || rencode('1951')); -- MCMLI DBMS_OUTPUT.PUT_LINE ('1987 = ' || rencode('1987')); -- MCMLXXXVII DBMS_OUTPUT.PUT_LINE ('1666 = ' || rencode('1666')); -- MDCLXVI DBMS_OUTPUT.PUT_LINE ('1999 = ' || rencode('1999')); -- MCMXCIX END; ## Plain TeX TeX has its own way to convert a number into roman numeral, but it produces lowercase letters; the following macro (and usage example), produce uppercase roman numeral. \def\upperroman#1{\uppercase\expandafter{\romannumeral#1}} Anno Domini \upperroman{\year} \bye ## PowerShell Filter ToRoman {$output = ''

if ($_ -ge 4000) { throw 'Number too high' }$current = 1000
$subtractor = 'M'$whole = $False$decimal = $_ 'C','D','X','L','I','V',' '  | %{$divisor = $current if ($whole = !$whole) {$current /= 10
$subtractor =$_ + $subtractor[0]$_ = $subtractor[1] } else {$divisor *= 5
$subtractor =$subtractor[0] + $_ }$multiple = [Math]::floor($decimal /$divisor)
if ($multiple) {$output += [string]$_ *$multiple
$decimal %=$divisor
}
if ($decimal -ge ($divisor -= $current)) {$output += $subtractor$decimal -= $divisor } }$output
}
19,4,0,2479,3001 | ToRoman
Output:
XIX
IV

MMCDLXXIX
MMMI


## Prolog

Works with: SWI-Prolog
Library: clpfd

Library clpfd assures that the program works in both managements : Roman towards Arabic and Arabic towards Roman.

:- use_module(library(clpfd)).

roman :-
LA =  [    _       , 2010,    _, 1449,         _],
LR =  ['MDCCLXXXIX',  _  , 'CX',    _, 'MDCLXVI'],
maplist(roman,   LA, LR),
maplist(my_print,LA, LR).

roman(A, R) :-
A #> 0,
roman(A, [u, t, h, th], LR, []),
label([A]),
parse_Roman(CR, LR, []),
atom_chars(R, CR).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% using DCG

roman(0, []) --> [].

roman(N, [H | T]) -->
{N1 #= N / 10,
N2 #= N mod 10},
roman(N1, T),
unity(N2, H).

unity(1, u) --> ['I'].
unity(1, t) --> ['X'].
unity(1, h) --> ['C'].
unity(1, th)--> ['M'].

unity(4, u) --> ['IV'].
unity(4, t) --> ['XL'].
unity(4, h) --> ['CD'].
unity(4, th)--> ['MMMM'].

unity(5, u) --> ['V'].
unity(5, t) --> ['L'].
unity(5, h) --> ['D'].
unity(5, th)--> ['MMMMM'].

unity(9, u) --> ['IX'].
unity(9, t) --> ['XC'].
unity(9, h) --> ['CM'].
unity(9, th)--> ['MMMMMMMMM'].

unity(0, _) --> [].

unity(V, U)-->
{V #> 5,
V1 #= V - 5},
unity(5, U),
unity(V1, U).

unity(V, U) -->
{V #> 1, V #< 4,
V1 #= V-1},
unity(1, U),
unity(V1, U).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Extraction of roman "lexeme"
parse_Roman(['C','M'|T]) -->
['CM'],
parse_Roman(T).

parse_Roman(['C','D'|T]) -->
['CD'],
parse_Roman(T).

parse_Roman(['X','C'| T]) -->
['XC'],
parse_Roman(T).

parse_Roman(['X','L'| T]) -->
['XL'],
parse_Roman(T).

parse_Roman(['I','X'| T]) -->
['IX'],
parse_Roman(T).

parse_Roman(['I','V'| T]) -->
['IV'],
parse_Roman(T).

parse_Roman([H | T]) -->
[H],
parse_Roman(T).

parse_Roman([]) -->
[].

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
my_print(A, R) :-
format('~w in roman is ~w~n', [A, R]).
Output:
 ?- roman.
1789 in roman is MDCCLXXXIX
2010 in roman is MMX
110 in roman is CX
1449 in roman is MCDXLIX
1666 in roman is MDCLXVI
true .


## Python

### Pythonic

import roman
print(roman.toRoman(2022))

### Minimalistic structuralism

def toRoman(n):
res=''		#converts int to str(Roman numeral)
reg=n		#using the numerals (M,D,C,L,X,V,I)
if reg<4000:#no more than three repetitions
while reg>=1000:	#thousands up to MMM
res+='M'		#MAX is MMMCMXCIX
reg-=1000
if reg>=900:		#nine hundreds in 900-999
res+='CM'
reg-=900
if reg>=500:		#five hudreds in 500-899
res+='D'
reg-=500
if reg>=400:		#four hundreds in 400-499
res+='CD'
reg-=400
while reg>=100:		#hundreds in 100-399
res+='C'
reg-=100
if reg>=90:			#nine tens in 90-99
res+='XC'
reg-=90
if reg>=50:			#five Tens in 50-89
res+='L'
reg-=50
if reg>=40:
res+='XL'		#four Tens
reg-=40
while reg>=10:
res+="X"		#tens
reg-=10
if reg>=9:
res+='IX'		#nine Units
reg-=9
if reg>=5:
res+='V'		#five Units
reg-=5
if reg>=4:
res+='IV'		#four Units
reg-=4
while reg>0:		#three or less Units
res+='I'
reg-=1
return res

### Imperative

1. Version for Python 2
roman =        "MDCLXVmdclxvi"; # UPPERCASE for thousands #
arabic =       (1000000, 500000, 100000, 50000, 10000, 5000, 1000, 500, 100, 50, 10, 5, 1);
adjust_arabic = (100000, 100000,  10000, 10000,  1000, 1000,  100, 100,  10, 10,  1, 1, 0);

def arabic_to_roman(dclxvi):
org = dclxvi; # 666 #
out = "";
for scale,arabic_scale  in enumerate(arabic):
if org == 0: break
multiples = org / arabic_scale;
org -= arabic_scale * multiples;
out += roman[scale] * multiples;
if org >= -adjust_arabic[scale] + arabic_scale:
return out

if __name__ == "__main__":
test = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,25,30,40,50,60,69,70,
80,90,99,100,200,300,400,500,600,666,700,800,900,1000,1009,1444,1666,1945,1997,1999,
2000,2008,2500,3000,4000,4999,5000,6666,10000,50000,100000,500000,1000000);
for val in test:
print '%d - %s'%(val, arabic_to_roman(val))

An alternative which uses the divmod() function

romanDgts= 'ivxlcdmVXLCDM_'

def ToRoman(num):
namoR = ''
if num >=4000000:
print 'Too Big -'
return '-----'
for rdix in range(0, len(romanDgts), 2):
if num==0: break
num,r = divmod(num,10)
v,r = divmod(r, 5)
if r==4:
namoR += romanDgts[rdix+1+v] + romanDgts[rdix]
else:
namoR += r*romanDgts[rdix] + (romanDgts[rdix+1] if(v==1) else '')
return namoR[-1::-1]

It is more Pythonic to use zip to iterate over two lists together:

anums = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
rnums = "M CM D CD C XC L XL X IX V IV I".split()

def to_roman(x):
ret = []
for a,r in zip(anums, rnums):
n,x = divmod(x,a)
ret.append(r*n)
return ''.join(ret)

if __name__ == "__main__":
test = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,25,30,40,
50,60,69,70,80,90,99,100,200,300,400,500,600,666,700,800,900,
1000,1009,1444,1666,1945,1997,1999,2000,2008,2010,2011,2500,
3000,3999)

for val in test:
print '%d - %s'%(val, to_roman(val))
1. Version for Python 3
def arabic_to_roman(dclxvi):
#===========================
'''Convert an integer from the decimal notation to the Roman notation'''
org = dclxvi; # 666 #
out = "";
for scale, arabic_scale  in enumerate(arabic):
if org == 0: break
multiples = org // arabic_scale;
org -= arabic_scale * multiples;
out += roman[scale] * multiples;
if (org >= -adjust_arabic[scale] + arabic_scale):
return out

if __name__ == "__main__":
test = (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,25,30,40,50,60,69,70,
80,90,99,100,200,300,400,500,600,666,700,800,900,1000,1009,1444,1666,1945,1997,1999,
2000,2008,2500,3000,4000,4999,5000,6666,10000,50000,100000,500000,1000000);

for val in test:
print("%8d %s" %(val, arabic_to_roman(val)))

### Declarative

Less readable, but a 'one liner':

rnl = [ { '4' : 'MMMM', '3' : 'MMM', '2' : 'MM', '1' : 'M', '0' : '' }, { '9' : 'CM', '8' : 'DCCC', '7' : 'DCC',
'6' : 'DC', '5' : 'D', '4' : 'CD', '3' : 'CCC', '2' : 'CC', '1' : 'C', '0' : '' }, { '9' : 'XC',
'8' : 'LXXX', '7' : 'LXX', '6' : 'LX', '5' : 'L', '4' : 'XL', '3' : 'XXX', '2' : 'XX', '1' : 'X',
'0' : '' }, { '9' : 'IX', '8' : 'VIII', '7' : 'VII', '6' : 'VI', '5' : 'V', '4' : 'IV', '3' : 'III',
'2' : 'II', '1' : 'I', '0' : '' }]
# Option 1
def number2romannumeral(n):
return ''.join([rnl[x][y] for x, y in zip(range(4), str(n).zfill(4)) if n < 5000 and n > -1])
# Option 2
def number2romannumeral(n):
return reduce(lambda x, y: x + y, map(lambda x, y: rnl[x][y], range(4), str(n).zfill(4))) if -1 < n < 5000 else None

Or, defining roman in terms of mapAccumL:

Works with: Python version 3
'''Encoding Roman Numerals'''

from functools import reduce
from itertools import chain

# romanFromInt ::  Int -> String
def romanFromInt(n):
'''A string of Roman numerals encoding an integer.'''
def go(a, ms):
m, s = ms
q, r = divmod(a, m)
return (r, s * q)

return concat(snd(mapAccumL(go)(n)(
zip([
1000, 900, 500, 400, 100, 90, 50,
40, 10, 9, 5, 4, 1
], [
'M', 'CM', 'D', 'CD', 'C', 'XC', 'L',
'XL', 'X', 'IX', 'V', 'IV', 'I'
])
)))

# ------------------------- TEST -------------------------
# main :: IO ()
def main():
'''Sample of years'''
for s in [
romanFromInt(x) for x in [
1666, 1990, 2008, 2016, 2018, 2020
]
]:
print(s)

# ------------------ GENERIC FUNCTIONS -------------------

# concat :: [[a]] -> [a]
# concat :: [String] -> String
def concat(xxs):
'''The concatenation of all the elements in a list.'''
xs = list(chain.from_iterable(xxs))
unit = '' if isinstance(xs, str) else []
return unit if not xs else (
''.join(xs) if isinstance(xs[0], str) else xs
)

# mapAccumL :: (acc -> x -> (acc, y)) -> acc -> [x] -> (acc, [y])
def mapAccumL(f):
'''A tuple of an accumulation and a list derived by a
combined map and fold,
with accumulation from left to right.'''
def go(a, x):
tpl = f(a[0], x)
return (tpl[0], a[1] + [tpl[1]])
return lambda acc: lambda xs: (
reduce(go, xs, (acc, []))
)

# snd :: (a, b) -> b
def snd(tpl):
'''Second component of a tuple.'''
return tpl[1]

# MAIN ---
if __name__ == '__main__':
main()
Output:
MDCLXVI
MCMXC
MMVIII
MMXVI
MMXVIII
MMXX

## Quackery

Pasting epitomised.

  [ $"" swap 1000 /mod$ "M" rot of rot swap join swap
dup   900 < not if [ 900 - dip [ $"CM" join ] ] dup 500 < not if [ 500 - dip [$  "D" join ] ]
dup   400 < not if [ 400 - dip [ $"CD" join ] ] 100 /mod$ "C" rot of rot swap join swap
dup    90 < not if [  90 - dip [ $"XC" join ] ] dup 50 < not if [ 50 - dip [$  "L" join ] ]
dup    40 < not if [  40 - dip [ $"XL" join ] ] 10 /mod$ "X" rot of rot swap join swap
dup     9 < not if [   9 - dip [ $"IX" join ] ] dup 5 < not if [ 5 - dip [$  "V" join ] ]
dup     4 < not if [   4 - dip [ $"IV" join ] ]$ "I" swap of join ]
is ->roman ( n --> $) 1990 dup echo say " = " ->roman echo$ cr
2008 dup echo say " = " ->roman echo$cr 1666 dup echo say " = " ->roman echo$ cr
Output:
1990 = MCMXC
2008 = MMVIII
1666 = MDCLXVI

## R

R has a built-in function, as.roman, for conversion to Roman numerals. The implementation details are found in utils:::.numeric2roman (see previous link), and utils:::.roman2numeric, for conversion back to Arabic decimals.

as.roman(1666)   # MDCLXVI

Since the object as.roman creates is just an integer vector with a class, you can do arithmetic with Roman numerals:

as.roman(1666) + 334   # MM

## Racket

Straight recursion:

#lang racket
(define (encode/roman number)
(cond ((>= number 1000) (string-append "M" (encode/roman (- number 1000))))
((>= number 900) (string-append "CM" (encode/roman (- number 900))))
((>= number 500) (string-append "D" (encode/roman (- number 500))))
((>= number 400) (string-append "CD" (encode/roman (- number 400))))
((>= number 100) (string-append "C" (encode/roman (- number 100))))
((>= number 90) (string-append "XC" (encode/roman (- number 90))))
((>= number 50) (string-append "L" (encode/roman (- number 50))))
((>= number 40) (string-append "XL" (encode/roman (- number 40))))
((>= number 10) (string-append "X" (encode/roman (- number 10))))
((>= number 9) (string-append "IX" (encode/roman (- number 9))))
((>= number 5) (string-append "V" (encode/roman (- number 5))))
((>= number 4) (string-append "IV" (encode/roman (- number 4))))
((>= number 1) (string-append "I" (encode/roman (- number 1))))
(else "")))

Using for/fold and quotient/remainder to remove repetition:

#lang racket
(define (number->list n)
(for/fold ([result null])
([decimal '(1000 900 500 400 100 90 50 40 10 9  5 4  1)]
[roman   '(M    CM  D   CD  C   XC L  XL X  IX V IV I)])
#:break (= n 0)
(let-values ([(q r) (quotient/remainder n decimal)])
(set! n r)
(append result (make-list q roman)))))

(define (encode/roman number)
(string-join (map symbol->string (number->list number)) ""))

(for ([n '(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 25 30 40
50 60 69 70 80 90 99 100 200 300 400 500 600 666 700 800 900
1000 1009 1444 1666 1945 1997 1999 2000 2008 2010 2011 2500
3000 3999)])
(printf "~a ~a\n" n (encode/roman n)))

## Raku

(formerly Perl 6)

my %symbols =
1 => "I", 5 => "V", 10 => "X", 50 => "L", 100 => "C",
500 => "D", 1_000 => "M";

my @subtractors =
1_000, 100,  500, 100,  100, 10,  50, 10,  10, 1,  5, 1,  1, 0;

multi sub roman (0) { '' }
multi sub roman (Int $n) { for @subtractors ->$cut, $minus {$n >= $cut and return %symbols{$cut} ~ roman($n -$cut);
$n >=$cut - $minus and return %symbols{$minus} ~ roman($n +$minus);
}
}

# Sample usage

for 1 .. 2_010 -> $x { say roman($x);
}

## Red

Straight iterative solution:

Red []

table: [1000 M 900 CM 500 D 400 CD 100 C 90 XC 50 L 40 XL 10 X 9 IX 5 V 4 IV 1 I]

to-Roman: function [n [integer!] return: [string!]][
out: copy ""
foreach [a r] table [while [n >= a][append out r n: n - a]]
out
]

foreach number [40 33 1888 2016][print [number ":" to-Roman number]]

Straight recursive solution:

Red []

table: [1000 M 900 CM 500 D 400 CD 100 C 90 XC 50 L 40 XL 10 X 9 IX 5 V 4 IV 1 I]

to-Roman: func [n [integer!] return: [string!]][
case [
tail? table [table: head table copy ""]
table/1 > n [table: skip table 2 to-Roman n]
'else       [append copy form table/2 to-Roman n - table/1]
]
]

foreach number [40 33 1888 2016][print [number ":" to-Roman number]]

This solution builds, using metaprogramming, a case table, that relies on recursion to convert every digit.

Red []

to-Roman: function [n [integer!]] reduce [
'case collect [
foreach [a r] [1000 M 900 CM 500 D 400 CD 100 C 90 XC 50 L 40 XL 10 X 9 IX 5 V 4 IV 1 I][
keep compose/deep [n >= (a) [append copy (form r) any [to-Roman n - (a) copy ""]]]
]
]
]

foreach number [40 33 1888 2016][print [number ":" to-Roman number]]

## Retro

This is a port of the Forth code; but returns a string rather than displaying the roman numerals. It only handles numbers between 1 and 3999.

: vector ( ...n"- )
here [ &, times ] dip : .data  swap  +  @  do  ; ;
: .I  dup     @ ^buffer'add ;
: .V  dup 1 + @ ^buffer'add ;
: .X  dup 2 + @ ^buffer'add ;

[ .I .X       drop ]
[ .V .I .I .I drop ]
[ .V .I .I    drop ]
[ .V .I       drop ]
[ .V          drop ]
[ .I .V       drop ]
[ .I .I .I    drop ]
[ .I .I       drop ]
[ .I          drop ]
&drop
10 vector .digit

: record ( an- )
10 /mod dup [ [ over 2 + ] dip record ] &drop if .digit ;
: toRoman   ( n-a )
here ^buffer'set
dup 1 3999 within 0 =
[ "EX LIMITO!\n" ] [ "IVXLCDM" swap record here ] if ;

## REXX

### version 1

roman: procedure
arg number

/* handle only 1 to 3999, else return ? */
if number >= 4000 | number <= 0 then return "?"

romans = "   M  CM   D  CD   C  XC  L  XL  X IX  V IV  I"
arabic = "1000 900 500 400 100  90 50  40 10  9  5  4  1"

result = ""
do i = 1 to words(romans)
do while number >= word(arabic,i)
result = result || word(romans,i)
number = number - word(arabic,i)
end
end
return result

### version 2

This version of a REXX program allows almost any non-negative decimal integer.

Most people think that the Romans had no word for "zero".   The Roman numeral system has no need for a
zero   placeholder,   so there was no name for it   (just as we have no name for a   "¶"   in the middle of our
numbers ─── as we don't have that possibility).   However, the Romans did have a name for zero (or nothing).
In fact the Romans had several names for zero   (see the REXX code),   as does modern English.   In American
English, many words can be used for   0:     zero, nothing, naught, bupkis, zilch, goose-egg, nebbish, squat, nil,
crapola, what-Patty-shot-at, nineteen (only in cribbage), love (in tennis), etc.

Also, this REXX version supports large numbers (with parentheses and deep parentheses).

(This REXX code was ripped out of my general routine that also supported versions for Attic, ancient Roman,
and modern Roman numerals.)

The general REXX code is bulkier than most at it deals with   any   non-negative decimal number,   and more
boilerplate code is in the general REXX code to handle the above versions.

/*REXX program converts (Arabic) non─negative decimal integers (≥0) ───► Roman numerals.*/
numeric digits 10000                             /*decimal digs can be higher if wanted.*/
parse arg #                                      /*obtain optional integers from the CL.*/
@er= "argument isn't a non-negative integer: "   /*literal used when issuing error msg. */
if #=''  then                                    /*Nothing specified?  Then generate #s.*/
do
do j= 0  by  11  to  111; #=# j;     end
#=# 49;                                       do k=88  by 100  to 1200; #=# k;     end
#=# 1000 2000 3000 4000 5000 6000;            do m=88  by 200  to 1200; #=# m;     end
#=# 1304 1405 1506 1607 1708 1809 1910 2011;  do p= 4          to   50; #=# 10**p; end
end                                          /*finished with generation of numbers. */

do i=1  for words(#);         x=word(#, i)     /*convert each of the numbers───►Roman.*/
if \datatype(x, 'W') | x<0  then say "***error***"  @er  x     /*¬ whole #?  negative?*/
say  right(x, 55)     dec2rom(x)
end   /*i*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
dec2rom: procedure;   parse arg n,#              /*obtain the number, assign # to a null*/
n=space(translate(n/1, , ','),  0)      /*remove commas from normalized integer*/
nulla= 'ZEPHIRUM NULLAE NULLA NIHIL'    /*Roman words for "nothing" or "none". */
if n==0  then return word(nulla, 1)     /*return a Roman word for  "zero".     */
maxnp=(length(n)-1)%3                   /*find max(+1) # of parenthesis to use.*/
highPos=(maxnp+1)*3                     /*highest position of number.          */
nn=reverse( right(n, highPos, 0) )      /*digits for Arabic──►Roman conversion.*/
do j=highPos  to 1  by -3
_=substr(nn, j,   1);  select     /*════════════════════hundreds.*/
when _==9  then hx='CM'
when _>=5  then hx='D'copies("C", _-5)
when _==4  then hx='CD'
otherwise       hx=   copies('C', _)
end  /*select hundreds*/
_=substr(nn, j-1, 1);  select     /*════════════════════════tens.*/
when _==9  then tx='XC'
when _>=5  then tx='L'copies("X", _-5)
when _==4  then tx='XL'
otherwise       tx=   copies('X', _)
end  /*select tens*/
_=substr(nn, j-2, 1);  select     /*═══════════════════════units.*/
when _==9  then ux='IX'
when _>=5  then ux='V'copies("I", _-5)
when _==4  then ux='IV'
otherwise       ux=   copies('I', _)
end  /*select units*/
$=hx || tx || ux if$\==''  then #=# || copies("(", (j-1)%3)||copies(')', (j-1)%3) end /*j*/ if pos('(I',#)\==0 then do i=1 for 4 /*special case: M,MM,MMM,MMMM.*/ if i==4 then _ = '(IV)' else _ = '('copies("I", i)')' if pos(_, #)\==0 then #=changestr(_, #, copies('M', i)) end /*i*/ return # Some older REXXes don't have a changestr BIF, so one is included here ──► CHANGESTR.REX. output when using the default (internal) input):  0 ZEPHIRUM 11 XI 22 XXII 33 XXXIII 44 XLIV 55 LV 66 LXVI 77 LXXVII 88 LXXXVIII 99 XCIX 110 CX 49 XLIX 88 LXXXVIII 188 CLXXXVIII 288 CCLXXXVIII 388 CCCLXXXVIII 488 CDLXXXVIII 588 DLXXXVIII 688 DCLXXXVIII 788 DCCLXXXVIII 888 DCCCLXXXVIII 988 CMLXXXVIII 1088 MLXXXVIII 1188 MCLXXXVIII 1000 M 2000 MM 3000 MMM 4000 MMMM 5000 (V) 6000 (VI) 88 LXXXVIII 288 CCLXXXVIII 488 CDLXXXVIII 688 DCLXXXVIII 888 DCCCLXXXVIII 1088 MLXXXVIII 1304 MCCCIV 1405 MCDV 1506 MDVI 1607 MDCVII 1708 MDCCVIII 1809 MDCCCIX 1910 MCMX 2011 MMXI 10000 (X) 100000 (C) 1000000 (M) 10000000 ((X)) 100000000 ((C)) 1000000000 ((M)) 10000000000 (((X))) 100000000000 (((C))) 1000000000000 (((M))) 10000000000000 ((((X)))) 100000000000000 ((((C)))) 1000000000000000 ((((M)))) 10000000000000000 (((((X))))) 100000000000000000 (((((C))))) 1000000000000000000 (((((M))))) 10000000000000000000 ((((((X)))))) 100000000000000000000 ((((((C)))))) 1000000000000000000000 ((((((M)))))) 10000000000000000000000 (((((((X))))))) 100000000000000000000000 (((((((C))))))) 1000000000000000000000000 (((((((M))))))) 10000000000000000000000000 ((((((((X)))))))) 100000000000000000000000000 ((((((((C)))))))) 1000000000000000000000000000 ((((((((M)))))))) 10000000000000000000000000000 (((((((((X))))))))) 100000000000000000000000000000 (((((((((C))))))))) 1000000000000000000000000000000 (((((((((M))))))))) 10000000000000000000000000000000 ((((((((((X)))))))))) 100000000000000000000000000000000 ((((((((((C)))))))))) 1000000000000000000000000000000000 ((((((((((M)))))))))) 10000000000000000000000000000000000 (((((((((((X))))))))))) 100000000000000000000000000000000000 (((((((((((C))))))))))) 1000000000000000000000000000000000000 (((((((((((M))))))))))) 10000000000000000000000000000000000000 ((((((((((((X)))))))))))) 100000000000000000000000000000000000000 ((((((((((((C)))))))))))) 1000000000000000000000000000000000000000 ((((((((((((M)))))))))))) 10000000000000000000000000000000000000000 (((((((((((((X))))))))))))) 100000000000000000000000000000000000000000 (((((((((((((C))))))))))))) 1000000000000000000000000000000000000000000 (((((((((((((M))))))))))))) 10000000000000000000000000000000000000000000 ((((((((((((((X)))))))))))))) 100000000000000000000000000000000000000000000 ((((((((((((((C)))))))))))))) 1000000000000000000000000000000000000000000000 ((((((((((((((M)))))))))))))) 10000000000000000000000000000000000000000000000 (((((((((((((((X))))))))))))))) 100000000000000000000000000000000000000000000000 (((((((((((((((C))))))))))))))) 1000000000000000000000000000000000000000000000000 (((((((((((((((M))))))))))))))) 10000000000000000000000000000000000000000000000000 ((((((((((((((((X)))))))))))))))) 100000000000000000000000000000000000000000000000000 ((((((((((((((((C))))))))))))))))  ## Ring arabic = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1] roman = ["M", "CM", "D", "CD", "C" ,"XC", "L", "XL" ,"X", "IX", "V", "IV", "I"] see "2009 = " + toRoman(2009) + nl see "1666 = " + toRoman(1666) + nl see "3888 = " + toRoman(3888) + nl func toRoman val result = "" for i = 1 to 13 while val >= arabic[i] result = result + roman[i] val = val - arabic[i] end next return result ## RPL Translation of: Python Works with: Halcyon Calc version 4.2.7 RPL code Comment ≪ { 1000 900 500 400 100 90 50 40 10 9 5 4 1 } { "M" "CM" "D" "CD" "C" "XC" "L" "XL" "X" "IX" "V" "IV" "I" } → divs rdig IF DUP 5000 < THEN "" SWAP 1 13 FOR j divs j GET MOD LAST / IP ROT SWAP WHILE DUP REPEAT rdig j GET ROT SWAP + SWAP 1 - END DROP SWAP NEXT END DROP ≫ '→ROM' STO  →ROM ( n -- "ROMAN" ) store tables if n < 5000 then scan divisors x,y = divmod(n, divisor) if x > 0 then add related digit x times n = y clean stack  ### Alternate version RPL code Comment ≪ IF DUP 5000 < THEN { "IIIVIIIX" "XXXLXXXC" "CCCDCCCM" } { 11 21 31 43 44 54 64 74 87 88 } → rom args ≪ "" SWAP 1 3 FOR j 10 MOD LAST / IP IF SWAP THEN args LAST GET 10 MOD LAST / IP rom j GET ROT ROT SUB ROT + SWAP END NEXT ≫ WHILE DUP REPEAT 1 - "M" ROT + SWAP END DROP END ≫ '→ROM' STO  →ROM ( n -- "M..CXVI" ) collapsed Roman digits 10 arguments to extract Roman digits initialize stack process units to hundreds divmod(n,10) if last digit ≠ 0 then get extraction arguments extract Roman digit add thousands if any clean stack  ## Ruby Roman numeral generation was used as an example for demonstrating Test Driven Development in Ruby. The solution came to be: Symbols = { 1=>'I', 5=>'V', 10=>'X', 50=>'L', 100=>'C', 500=>'D', 1000=>'M' } Subtractors = [ [1000, 100], [500, 100], [100, 10], [50, 10], [10, 1], [5, 1], [1, 0] ] def roman(num) return Symbols[num] if Symbols.has_key?(num) Subtractors.each do |cutPoint, subtractor| return roman(cutPoint) + roman(num - cutPoint) if num > cutPoint return roman(subtractor) + roman(num + subtractor) if num >= cutPoint - subtractor and num < cutPoint end end [1990, 2008, 1666].each do |i| puts "%4d => %s" % [i, roman(i)] end Output: 1990 => MCMXC 2008 => MMVIII 1666 => MDCLXVI  Another shorter version if we don't consider calculating the substractors: Symbols = [ [1000, 'M'], [900, 'CM'], [500, 'D'], [400, 'CD'], [100, 'C'], [90, 'XC'], [50, 'L'], [40, 'XL'], [10, 'X'], [9, 'IX'], [5, 'V'], [4, 'IV'], [1, 'I'] ] def arabic_to_roman(arabic) return '' if arabic.zero? Symbols.each { |arabic_rep, roman_rep| return roman_rep + arabic_to_roman(arabic - arabic_rep) if arabic >= arabic_rep } end Yet another way to solve it in terms of reduce Symbols = [ [1000, 'M'], [900, 'CM'], [500, 'D'], [400, 'CD'], [100, 'C'], [90, 'XC'], [50, 'L'], [40, 'XL'], [10, 'X'], [9, 'IX'], [5, 'V'], [4, 'IV'], [1, 'I'] ] def to_roman(num) Symbols.reduce "" do |memo, (divisor, letter)| div, num = num.divmod(divisor) memo + letter * div end end ## Rust struct RomanNumeral { symbol: &'static str, value: u32 } const NUMERALS: [RomanNumeral; 13] = [ RomanNumeral {symbol: "M", value: 1000}, RomanNumeral {symbol: "CM", value: 900}, RomanNumeral {symbol: "D", value: 500}, RomanNumeral {symbol: "CD", value: 400}, RomanNumeral {symbol: "C", value: 100}, RomanNumeral {symbol: "XC", value: 90}, RomanNumeral {symbol: "L", value: 50}, RomanNumeral {symbol: "XL", value: 40}, RomanNumeral {symbol: "X", value: 10}, RomanNumeral {symbol: "IX", value: 9}, RomanNumeral {symbol: "V", value: 5}, RomanNumeral {symbol: "IV", value: 4}, RomanNumeral {symbol: "I", value: 1} ]; fn to_roman(mut number: u32) -> String { let mut min_numeral = String::new(); for numeral in NUMERALS.iter() { while numeral.value <= number { min_numeral = min_numeral + numeral.symbol; number -= numeral.value; } } min_numeral } fn main() { let nums = [2014, 1999, 25, 1666, 3888]; for &n in nums.iter() { // 4 is minimum printing width, for alignment println!("{:2} = {}", n, to_roman(n), 4);
}
}
Output:
2014 = MMXIV
1999 = MCMXCIX
25 = XXV
1666 = MDCLXVI
3888 = MMMDCCCLXXXVIII


## Scala

Works with: Scala version 2.8
val romanDigits = Map(
1 -> "I", 5 -> "V",
10 -> "X", 50 -> "L",
100 -> "C", 500 -> "D",
1000 -> "M",
4 -> "IV", 9 -> "IX",
40 -> "XL", 90 -> "XC",
400 -> "CD", 900 -> "CM")
val romanDigitsKeys = romanDigits.keysIterator.toList sortBy (x => -x)
def toRoman(n: Int): String = romanDigitsKeys find (_ >= n) match {
case Some(key) => romanDigits(key) + toRoman(n - key)
case None => ""
}
Output:
scala> List(1990, 2008, 1666) map toRoman
res55: List[String] = List(MCMXC, MMVIII, MDCLXVI)

### Using foldLeft

def toRoman( v:Int ) : String = {
val romanNumerals = List(1000->"M",900->"CM",500->"D",400->"CD",100->"C",90->"XC",
50->"L",40->"XL",10->"X",9->"IX",5->"V",4->"IV",1->"I")

var n = v
romanNumerals.foldLeft(""){(s,t) => {val c = n/t._1; n = n-t._1*c;  s + (t._2 * c) } }
}

// A small test
def test( arabic:Int ) = println( arabic + " => " + toRoman( arabic ) )

test(1990)
test(2008)
test(1666)

### Different code-style

def toRoman(num: Int): String = {
case class RomanUnit(value: Int, token: String)
val romanNumerals = List(
RomanUnit(1000, "M"),
RomanUnit(900, "CM"),
RomanUnit(500, "D"),
RomanUnit(400, "CD"),
RomanUnit(100, "C"),
RomanUnit(90, "XC"),
RomanUnit(50, "L"),
RomanUnit(40, "XL"),
RomanUnit(10, "X"),
RomanUnit(9, "IX"),
RomanUnit(5, "V"),
RomanUnit(4, "IV"),
RomanUnit(1, "I"))

var remainingNumber = num
romanNumerals.foldLeft("") { (outputStr, romanUnit) =>
{
val times = remainingNumber / romanUnit.value
remainingNumber -= romanUnit.value * times
outputStr + (romanUnit.token * times)
}
}
}
Output:
1990 => MCMXC
2008 => MMVIII
1666 => MDCLXVI

## Scheme

This uses format directives supported in Chez Scheme since v6.9b; YMMV.

(define (to-roman n)
(format "~@r" n))

This is a general example using Chicken Scheme.

(define roman-decimal
'(("M"  . 1000)
("CM" . 900)
("D"  . 500)
("CD" . 400)
("C"  . 100)
("XC" .  90)
("L"  .  50)
("XL" .  40)
("X"  .  10)
("IX" .   9)
("V"  .   5)
("IV" .   4)
("I"  .   1)))

(define (to-roman value)
(apply string-append
(let loop ((v value)
(decode roman-decimal))
(let ((r (caar decode))
(d (cdar decode)))
(cond
((= v 0) '())
((>= v d) (cons r (loop (- v d) decode)))
(else (loop v (cdr decode))))))))

(let loop ((n '(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 25 30 40
50 60 69 70 80 90 99 100 200 300 400 500 600 666 700 800 900
1000 1009 1444 1666 1945 1997 1999 2000 2008 2010 2011 2500
3000 3999)))
(unless (null? n)
(printf "~a ~a\n" (car n) (to-roman (car n)))
(loop (cdr n))))

## Seed7

The following program writes the numbers between 1 and 3999 as roman numerals. The wrinum.s7i library contains the function str(ROMAN,), which writes a roman numeral to a string.

$include "seed7_05.s7i"; include "stdio.s7i"; include "wrinum.s7i"; const proc: main is func local var integer: number is 0; begin for number range 1 to 3999 do writeln(str(ROMAN, number)); end for; end func; Original source [1]. ## SenseTalk function RomanNumeralsEncode number put [ (1, "I"), (4, "IV"), (5, "V"), (9, "IX"), (10, "X"), (40, "XL"), (50, "L"), (90, "XC"), (100, "C"), (400, "CD"), (500, "D"), (900, "CM"), (1000, "M") ] into values repeat for index = each item of (the number of items in values)..1 put item index of values into pair repeat while number is greater than or equal to the first item of pair put the second item of pair after numerals subtract the first item of pair from number end repeat end repeat return numerals end RomanNumeralsEncode repeat for each item in [ 1990, 2008, 1666 ] put RomanNumeralsEncode(it) end repeat Output: MCMXC MMVIII MDCLXVI  ## SETL examples := [2008, 1666, 1990]; for example in examples loop print( roman_numeral(example) ); end loop; proc roman_numeral( n ); R := [[1000, 'M'], [900, 'CM'], [500, 'D'], [400, 'CD'], [100, 'C'], [90, 'XC'], [50, 'L'], [40, 'XL'], [10, 'X'], [9, 'IX'], [5, 'V'], [4, 'IV'], [1, 'I']]; roman := ''; for numeral in R loop while n >= numeral(1) loop n := n - numeral(1); roman := roman + numeral(2); end loop; end loop; return roman; end; Output: MMVIII MDCLXVI MCMXC ## Shen (define encodeGlyphs ACC 0 _ -> ACC ACC N [Glyph Value | Rest] -> (encodeGlyphs (@s ACC Glyph) (- N Value) [Glyph Value | Rest]) where (>= N Value) ACC N [Glyph Value | Rest] -> (encodeGlyphs ACC N Rest) ) (define encodeRoman N -> (encodeGlyphs "" N ["M" 1000 "CM" 900 "D" 500 "CD" 400 "C" 100 "XC" 90 "L" 50 "XL" 40 "X" 10 "IX" 9 "V" 5 "IV" 4 "I" 1]) ) Output: (4-) (encodeRoman 1990) "MCMXC" (5-) (encodeRoman 2008) "MMVIII" (6-) (encodeRoman 1666) "MDCLXVI"  ## Sidef Translation of: ActionScript func arabic2roman(num, roman='') { static lookup = [ :M:1000, :CM:900, :D:500, :CD:400, :C:100, :XC:90, :L:50, :XL:40, :X:10, :IX:9, :V:5, :IV:4, :I:1 ]; lookup.each { |pair| while (num >= pair.second) { roman += pair.first; num -= pair.second; } } return roman; } say("1990 in roman is " + arabic2roman(1990)); say("2008 in roman is " + arabic2roman(2008)); say("1666 in roman is " + arabic2roman(1666)); Output: 1990 in roman is MCMXC 2008 in roman is MMVIII 1666 in roman is MDCLXVI ## Simula BEGIN TEXT PROCEDURE TOROMAN(N); INTEGER N; BEGIN PROCEDURE P(WEIGHT,LIT); INTEGER WEIGHT; TEXT LIT; BEGIN WHILE N >= WEIGHT DO BEGIN T :- T & LIT; N := N - WEIGHT; END WHILE; END P; TEXT T; T :- NOTEXT; P( 1000, "M" ); P( 900, "CM" ); P( 500, "D" ); P( 400, "CD" ); P( 100, "C" ); P( 90, "XC" ); P( 50, "L" ); P( 40, "XL" ); P( 10, "X" ); P( 9, "IX" ); P( 5, "V" ); P( 4, "IV" ); P( 1, "I" ); TOROMAN :- T; END TOROMAN; INTEGER Y; FOR Y := 1990, 2008, 1666 DO BEGIN OUTTEXT("YEAR "); OUTINT(Y, 4); OUTTEXT(" => "); OUTTEXT(TOROMAN(Y)); OUTIMAGE; END FOR; END PROGRAM; Output: YEAR 1990 => MCMXC YEAR 2008 => MMVIII YEAR 1666 => MDCLXVI  ## Smalltalk Works with: Smalltalk/X in ST/X, integers already know how to print themselves as roman number: 2013 printRomanOn:Stdout naive:false Output: MMXIII the implementation is: printRomanOn:aStream naive:naive "print the receiver as roman number to the argument, aStream. The naive argument controls if the conversion is correct (i.e. subtracting prefix notation for 4,9,40,90, etc.), or naive (i.e. print 4 as IIII and 9 as VIIII); also called simple. The naive version is often used for page numbers in documents." |restValue spec| restValue := self. restValue > 0 ifFalse:[self error:'negative roman']. naive ifTrue:[ spec := #( " value string repeat " 1000 'M' true 500 'D' false 100 'C' true 50 'L' false 10 'X' true 5 'V' false 1 'I' true ). ] ifFalse:[ spec := #( " value string repeat " 1000 'M' true 900 'CM' false 500 'D' false 400 'CD' false 100 'C' true 90 'XC' false 50 'L' false 40 'XL' false 10 'X' true 9 'IX' false 5 'V' false 4 'IV' false 1 'I' true ). ]. spec inGroupsOf:3 do:[:rValue :rString :repeatFlag | [ (restValue >= rValue) ifTrue:[ aStream nextPutAll:rString. restValue := restValue - rValue. ]. ] doWhile:[ repeatFlag and:[ restValue >= rValue] ]. ]. ## SNOBOL4 Adapted from Catspaw SNOBOL Tutorial, Chapter 6 * ROMAN(N) - Convert integer N to Roman numeral form. * * N must be positive and less than 4000. * * An asterisk appears in the result if N >= 4000. * * The function fails if N is not an integer. DEFINE('ROMAN(N)UNITS') :(ROMAN_END) * Get rightmost digit to UNITS and remove it from N. * Return null result if argument is null. ROMAN N RPOS(1) LEN(1) . UNITS = :F(RETURN) * Search for digit, replace with its Roman form. * Return failing if not a digit. '0,1I,2II,3III,4IV,5V,6VI,7VII,8VIII,9IX,' UNITS + BREAK(',') . UNITS :F(FRETURN) * Convert rest of N and multiply by 10. Propagate a * failure return from recursive call back to caller. ROMAN = REPLACE(ROMAN(N), 'IVXLCDM', 'XLCDM**') + UNITS :S(RETURN) F(FRETURN) ROMAN_END * Testing OUTPUT = "1999 = " ROMAN(1999) OUTPUT = " 24 = " ROMAN(24) OUTPUT = " 944 = " ROMAN(944) END Output: 1999 = MCMXCIX 24 = XXIV 944 = CMXLIV  Here's a non-recursive version, and a Roman-to-Arabic converter to boot. * # Arabic to Roman define('roman(n)s,ch,val,str') :(roman_end) roman roman = ge(n,4000) n :s(return) s = 'M1000 CM900 D500 CD400 C100 XC90 L50 XL40 X10 IX9 V5 IV4 I1 ' rom1 s span(&ucase) . ch break(' ') . val span(' ') = :f(rom2) str = str dupl(ch,(n / val)) n = remdr(n,val) :(rom1) rom2 roman = str :(return) roman_end * # Roman to Arabic define('arabic(n)s,ch,val,sum,x') :(arabic_end) arabic s = 'M1000 D500 C100 L50 X10 V5 I1 ' n = reverse(n) arab1 n len(1) . ch = :f(arab2) s ch break(' ') . val val = lt(val,x) (-1 * val) sum = sum + val; x = val :(arab1) arab2 arabic = sum :(return) arabic_end * # Test and display tstr = '2010 1999 1492 1066 476 ' tloop tstr break(' ') . year span(' ') = :f(out) r = roman(year) rstr = rstr year '=' r ' ' astr = astr r '=' arabic(r) ' ' :(tloop) out output = rstr; output = astr end Output: 2010=MMX 1999=MCMXCIX 1492=MCDXCII 1066=MLXVI 476=CDLXXVI MMX=2010 MCMXCIX=1999 MCDXCII=1492 MLXVI=1066 CDLXXVI=476 ## SPL a2r(a)= r = "" n = [["M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"],[1000,900,500,400,100,90,50,40,10,9,5,4,1]] > i, 1..13 > a!<n[i,2] r += n[i,1] a -= n[i,2] < < <= r . t = [1990,2008,1666] > i, 1..#.size(t,1) #.output(t[i]," = ",a2r(t[i])) < Output: 1990 = MCMXC 2008 = MMVIII 1666 = MDCLXVI  ## SQL -- -- This only works under Oracle and has the limitation of 1 to 3999 SQL> select to_char(1666, 'RN') urcoman, to_char(1666, 'rn') lcroman from dual; URCOMAN LCROMAN --------------- --------------- MDCLXVI mdclxvi ## Swift func ator(var n: Int) -> String { var result = "" for (value, letter) in [( 1000, "M"), ( 900, "CM"), ( 500, "D"), ( 400, "CD"), ( 100, "C"), ( 90, "XC"), ( 50, "L"), ( 40, "XL"), ( 10, "X"), ( 9, "IX"), ( 5, "V"), ( 4, "IV"), ( 1, "I")] { while n >= value { result += letter n -= value } } return result } Sample call: Works with: Swift version 1.x println(ator(1666)) // MDCLXVI Works with: Swift version 2.0 print(ator(1666)) // MDCLXVI Output: MDCLXVI  ## Tailspin def digits: [(M:1000"1"), (CM:900"1"), (D:500"1"), (CD:400"1"), (C:100"1"), (XC:90"1"), (L:50"1"), (XL:40"1"), (X:10"1"), (IX:9"1"), (V:5"1"), (IV:4"1"), (I:1"1")]; templates encodeRoman @: 1; '$ -> ($)"1" -> #;' ! when <$digits($@)::value..> do$digits($@)::key !$ - $digits($@)::value -> #
when <1"1"..> do
@:$@ + 1;$ -> #
end encodeRoman

1990 -> encodeRoman -> !OUT::write
'
' -> !OUT::write
2008 -> encodeRoman -> !OUT::write
'
' -> !OUT::write
1666 -> encodeRoman -> !OUT::write
Output:
MCMXC
MMVIII
MDCLXVI


## Tcl

proc to_roman {i} {
set map {1000 M 900 CM 500 D 400 CD 100 C 90 XC 50 L 40 XL 10 X 9 IX 5 V 4 IV 1 I}
foreach {value roman} $map { while {$i >= $value} { append res$roman
incr i -$value } } return$res
}

## TUSCRIPT

 MODE TUSCRIPT
LOOP arab_number="1990'2008'1666"
roman_number = ENCODE (arab_number,ROMAN)
PRINT "Arabic number ",arab_number, " equals ", roman_number
ENDLOOP
Output:
Arabic number 1990 equals MCMXC
Arabic number 2008 equals MMVIII
Arabic number 1666 equals MDCLXVI


## TypeScript

Translation of: DWScript

Weights and symbols in tuples.

// Roman numerals/Encode

const weightsSymbols: [number, string][] =
[[1000, 'M'], [900, 'CM'], [500, 'D'], [400, 'CD'], [100, 'C'], [90, 'XC'],
[50, 'L'], [40, 'XL'], [10, 'X'], [9, 'IX'], [5, 'V'], [4, 'IV'], [1, 'I']];
// 3888 or MMMDCCCLXXXVIII (15 chars) is the longest string properly encoded
// with these symbols.

function toRoman(n: number): string {
var roman = ""; // Result
for (i = 0; i <= 12 && n > 0; i++) {
var w = weightsSymbols[i][0];
while (n >= w) {
roman += weightsSymbols[i][1];
n -= w;
}
}
return roman;
}

console.log(toRoman(1990)); // MCMXC
console.log(toRoman(2022)); // MMXXII
console.log(toRoman(3888)); // MMMDCCCLXXXVIII
Output:
MCMXC
MMXXII
MMMDCCCLXXXVIII


## UNIX Shell

Translation of: Tcl
Works with: bash
roman() {
local values=( 1000 900 500 400 100 90 50 40 10 9 5 4 1 )
local roman=(
[1000]=M [900]=CM [500]=D [400]=CD
[100]=C  [90]=XC  [50]=L  [40]=XL
[10]=X   [9]=IX   [5]=V   [4]=IV
[1]=I
)
local nvmber=""
local num=$1 for value in${values[@]}; do
while (( num >= value )); do
nvmber+=${roman[value]} ((num -= value)) done done echo$nvmber
}

for test in 1999 24 944 1666 2008; do
printf "%d = %s\n" $test$(roman $test) done Output: 1999 = MCMXCIX 24 = XXIV 944 = CMXLIV 1666 = MDCLXVI 2008 = MMVIII ## Ursala The algorithm is to implement the subtractive principle by string substitution only after constucting the numeral from successive remainders. The order among the substitutions matters. For example, occurrences of DCCCC must be replaced by CM before any occurrences of CCCC are replaced by CD. The substitution operator (%=) is helpful here. #import nat roman = -+ 'IIII'%='IV'+ 'VIIII'%='IX'+ 'XXXX'%='XL'+ 'LXXXX'%='XC'+ 'CCCC'%='CD'+ 'DCCCC'%='CM', ~&plrDlSPSL/'MDCLXVI'+ iota*+ +^|(^|C/~&,\/division)@rlX=>~&iNC <1000,500,100,50,10,5>+- This test program applies the function to each member of a list of numbers. #show+ test = roman* <1990,2008,1,2,64,124,1666,10001> Output: MCMXC MMVIII I II LXIV CXXIV MDCLXVI MMMMMMMMMMI ## Vala Translation of: D string to_roman(int n) requires (n > 0 && n < 5000) { const int[] weights = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1}; const string[] symbols = {"M","CM","D","CD","C","XC","L", "XL","X","IX","V","IV","I"}; var roman = "", count = 0; foreach (var w in weights) { while (n >= w) { roman += symbols[count]; n -= w; } if (n == 0) break; count++; } return roman; } void main() { print("%s\n", to_roman(455)); print("%s\n", to_roman(3456)); print("%s\n", to_roman(2488)); } Output: CDLV MMMCDLVI MMCDLXXXVIII  ## VBA Private Function roman(n As Integer) As String roman = WorksheetFunction.roman(n) End Function Public Sub main() s = [{10, 2016, 800, 2769, 1666, 476, 1453}] For Each x In s Debug.Print roman(CInt(x)); " "; Next x End Sub Output: X MMXVI DCCC MMDCCLXIX MDCLXVI CDLXXVI MCDLIII  ## Vedit macro language // Main program for testing the function // do { #1 = Get_Num("Number to convert: ", STATLINE) Call("NUM_TO_ROMAN") Num_Type(#1, NOCR) Message(" = ") Reg_Type(1) Type_Newline } while (Reg_Size(1)) Return // Convert numeric value into Roman number // #1 = number to convert; on return: T-reg(1) = Roman number // :NUM_TO_ROMAN: Reg_Empty(1) // @1 = Results (Roman number) if (#1 < 1) { Return } // non-positive numbers return empty string Buf_Switch(Buf_Free) Ins_Text("M1000,CM900,D500,CD400,C100,XC90,L50,XL40,X10,IX9,V5,IV4,I1") BOF #2 = #1 Repeat(ALL) { Search("|A|[|A]", ADVANCE+ERRBREAK) // get next item from conversion list Reg_Copy_Block(20, CP-Chars_Matched, CP) // @20 = Letter(s) to be inserted #11 = Num_Eval() // #11 = magnitude (1000...1) while (#2 >= #11) { Reg_Set(1, @20, APPEND) #2 -= #11 } } Buf_Quit(OK) Return Output:  4 = IV 12 = XII 1666 = MDCLXVI 1990 = MCMXC 2011 = MMXI ## V (Vlang) const numerals = {1000:"M", 900:"CM", 500:"D", 400:"CD", 100:"C", 90:"XC", 50:"L", 40: "XL", 10:"X", 9:"IX", 5:"V", 4:"IV", 1:"I"} fn main() { println(encode(1990)) println(encode(2008)) println(encode(1666)) } fn encode(number int) string { mut num := number mut result := "" if number < 1 || number > 5000 {return result} for digit, roman in numerals { for num >= digit { num -= digit result += roman } } return result } Output: MCMXC MMVIII MDCLXVI  ## Wren Translation of: Kotlin var romans = [ [1000, "M"], [900, "CM"], [500, "D"], [400, "CD"], [100, "C"], [90, "XC"], [50, "L"], [40, "XL"], [10, "X"], [9, "IX"], [5, "V"], [4, "IV"], [1, "I"] ] var encode = Fn.new { |n| if (n > 5000 || n < 1) return null var res = "" for (r in romans) { while (n >= r[0]) { n = n - r[0] res = res + r[1] } } return res } System.print(encode.call(1990)) System.print(encode.call(1666)) System.print(encode.call(2008)) System.print(encode.call(2020)) Output: MCMXC MDCLXVI MMVIII MMXX  ## XLISP (defun roman (n) (define roman-numerals '((1000 "m") (900 "cm") (500 "d") (400 "cd") (100 "c") (90 "xc") (50 "l") (40 "xl") (10 "x") (9 "ix") (5 "v") (4 "iv") (1 "i"))) (defun romanize (arabic-numeral numerals roman-numeral) (if (= arabic-numeral 0) roman-numeral (if (>= arabic-numeral (caar numerals)) (romanize (- arabic-numeral (caar numerals)) numerals (string-append roman-numeral (cadar numerals))) (romanize arabic-numeral (cdr numerals) roman-numeral)))) (romanize n roman-numerals "")) ; test the function: (display (mapcar roman '(10 2016 800 2769 1666 476 1453))) Output: (x mmxvi dccc mmdcclxix mdclxvi cdlxxvi mcdliii) ## XPL0 proc Rom(N, A, B, C); \Display 1..9 in Roman numerals int N, A, B, C, I; [case N of 9: [ChOut(0, C); ChOut(0, A)]; \XI 8,7,6,5:[ChOut(0, B); for I:= 1 to rem(N/5) do ChOut(0, C)]; \V 4: [ChOut(0, C); ChOut(0, B)] \IV other for I:= 1 to N do ChOut(0, C); \I ]; proc Roman(N); \Display N in Roman numerals int N, Q; [Q:= N/1000; N:= rem(0); \0..3999 Rom(Q, ^?, ^?, ^M); Q:= N/100; N:= rem(0); \0..999 Rom(Q, ^M, ^D, ^C); Q:= N/10; N:= rem(0); \0..99 Rom(Q, ^C, ^L, ^X); Rom(N, ^X, ^V, ^I); \0..9 ]; int Tbl, I; [Tbl:= [1990, 2008, 1666, 0, 1, 3999, 2020, 1234]; for I:= 0 to 7 do [IntOut(0, Tbl(I)); Text(0, ". "); Roman(Tbl(I)); CrLf(0)]; ] Output: 1990. MCMXC 2008. MMVIII 1666. MDCLXVI 0. 1. I 3999. MMMCMXCIX 2020. MMXX 1234. MCCXXXIV  ## XSLT <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/data/number"> <xsl:call-template name="for"> <xsl:with-param name="stop">13</xsl:with-param> <xsl:with-param name="value"><xsl:value-of select="@value"></xsl:value-of></xsl:with-param> </xsl:call-template> </xsl:template> <xsl:template name="for"> <xsl:param name="start">1</xsl:param> <xsl:param name="stop">1</xsl:param> <xsl:param name="step">1</xsl:param> <xsl:param name="value">1</xsl:param> <xsl:text/> <xsl:choose> <xsl:when test="($value &gt; /data/roman
/numeral[@pos=$start]/@value or$value = /data/roman
/numeral[@pos=$start]/@value) "> <xsl:value-of select="/data/roman /numeral[@pos=$start]/@letter"/>
<xsl:call-template name="for">
<xsl:with-param name="stop">
<xsl:value-of select="$stop"/> </xsl:with-param> <xsl:with-param name="start"> <xsl:value-of select="$start"/>
</xsl:with-param>
<xsl:with-param name="value">
<xsl:value-of select="$value - /data/roman/numeral[@pos=$start]/@value"/>
</xsl:with-param>
</xsl:call-template>
</xsl:when>
<xsl:otherwise>
<xsl:if test="$start &lt;$stop">
<xsl:call-template name="for">
<xsl:with-param name="stop">
<xsl:value-of select="$stop"/> </xsl:with-param> <xsl:with-param name="start"> <xsl:value-of select="$start + $step"/> </xsl:with-param> <xsl:with-param name="value"> <xsl:value-of select="$value"/>
</xsl:with-param>
</xsl:call-template>
</xsl:if>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>

## zkl

var [const] romans = L(
L("M", 1000), L("CM", 900), L("D",  500), L("CD", 400), L("C",  100),
L("XC",  90), L("L",   50), L("XL",  40), L("X",   10), L("IX",   9),
L("V",    5), L("IV",   4), L("I",    1));
fcn toRoman(i){		// convert int to a roman number
reg text = "";
foreach R,N in (romans){ text += R*(i/N); i = i%N; }
return(text);
}
toRoman(1990) //-->"MCMXC"
toRoman(2008) //-->"MMVIII"
toRoman(1666) //-->"MDCLXVI"


## Zoea

program: decimal_roman
input: 12
output: 'XII'

## Zsh

Based on the python solution.

function printroman () {
local -a conv
local number=$1 div rom num out conv=(I 1 IV 4 V 5 IX 9 X 10 XL 40 L 50 XC 90 C 100 CD 400 D 500 CM 900 M 1000) for num rom in${(Oa)conv}; do
(( div = number / num, number = number % num ))
while (( div-- > 0 )); do
out+=$rom done done echo$out
}