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.
ActionScript
<lang 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)); </lang> Output:
1990 in roman is MCMXC 2008 in roman is MMVIII 1666 in roman is MDCLXVI
And the reverse: <lang ActionScript>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"));</lang> Output:
MCMXC in arabic is 1990 MMVIII in arabic is 2008 MDCLXVI in arabic is 1666
Ada
<lang ada>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;</lang> Output:
MCMXCIX XXV CMXLIV
ALGOL 68
<lang algol68>[]CHAR roman = "MDCLXVmdclxvi"; # UPPERCASE for thousands # []CHAR adjust roman = "CCXXmmccxxii"; []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
)</lang> 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
<lang algolw>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.</lang> Output:
I 1 MMMCMXCIX 9 MMMDCCCLXXXVIII 15 MMIX 4 CDV 3
AutoHotkey
<lang AutoHotkey>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"
}</lang>
AWK
<lang 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])
} </lang>
output:
1990 = MCMXC 2008 = MMVIII 1666 = MDCLXVI
BASIC
<lang 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) </lang>
Output
2009 = MMIX 1666 = MDCLXVI 3888 = MMMDCCCLXXXVIII
ZX Spectrum Basic
<lang zxbasic> 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$</lang>
BASIC256
<lang basic256> print 1666+" = "+convert$(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$[i] value = value - arabic[i] end while
next i
end function </lang> Output:
1666 = MDCLXVI 2008 = MMVIII 1001 = MI 1999 = MCMXCIX
BBC BASIC
<lang bbcbasic> PRINT ;1999, FNroman(1999)
PRINT ;2012, FNroman(2012)
PRINT ;1666, FNroman(1666)
PRINT ;3888, FNroman(3888)
END
DEF FNroman(n%)
LOCAL i%, r$, 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$(i%)
n% -= arabic%(i%)
ENDWHILE
NEXT
= r$</lang>
Output:
1999 MCMXCIX 2012 MMXII 1666 MDCLXVI 3888 MMMDCCCLXXXVIII
Bracmat
<lang 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")
)
)
);</lang> Output:
1990 MCMXC 2008 MMVIII 1666 MDCLXVI 3888 MMMDCCCLXXXVIII 3999 MMMCMXCIX Can't convert 4000 to Roman numeral
C
<lang c>#include <stdlib.h>
- include <stdio.h>
/*
* Writes the Roman numeral representing n into the buffer s. * Handles up to n = 3999. * Since C doesn't have exceptions, n = 0 causes the whole program to exit * unsuccessfully. * s should be have room for at least 16 characters, including the trailing * null. */
void roman(char *s, unsigned int n) {
if (n == 0)
{
fputs("Roman numeral for zero requested.", stderr);
exit(EXIT_FAILURE);
}
#define digit(loop, num, c) \
loop (n >= num) \
{*(s++) = c; \
n -= num;}
#define digits(loop, num, c1, c2) \
loop (n >= num) \
{*(s++) = c1; \
*(s++) = c2; \
n -= num;}
digit ( while, 1000, 'M' ) digits ( if, 900, 'C', 'M' ) digit ( if, 500, 'D' ) digits ( if, 400, 'C', 'D' ) digit ( while, 100, 'C' ) digits ( if, 90, 'X', 'C' ) digit ( if, 50, 'L' ) digits ( if, 40, 'X', 'L' ) digit ( while, 10, 'X' ) digits ( if, 9, 'I', 'X' ) digit ( if, 5, 'V' ) digits ( if, 4, 'I', 'V' ) digit ( while, 1, 'I' )
#undef digit #undef digits *s = 0;}
int main(void) {
char buffer[16];
unsigned int i;
for (i = 1 ; i < 4000 ; ++i)
{
roman(buffer, i);
printf("%4u: %s\n", i, buffer);
}
return EXIT_SUCCESS;
}</lang>
An alternative version which builds the string backwards. <lang c>char *ToRoman(int num, char *buf, int buflen) {
static const char romanDgts[] = "ivxlcdmVXLCDM_";
char *roman = buf + buflen;
int rdix, r, v;
*--roman = '\0'; /* null terminate return string */
if (num >= 4000000) {
printf("Number Too Big.\n");
return NULL;
}
for (rdix = 0; rdix < strlen(romanDgts); rdix += 2) {
if (num == 0) break;
v = (num % 10) / 5;
r = num % 5;
num = num / 10;
if (r == 4) {
if (roman < buf+2) {
printf("Buffer too small.");
return NULL;
}
*--roman = romanDgts[rdix+1+v];
*--roman = romanDgts[rdix];
}
else {
if (roman < buf+r+v) {
printf("Buffer too small.");
return NULL;
}
while(r-- > 0) {
*--roman = romanDgts[rdix];
}
if (v==1) {
*--roman = romanDgts[rdix+1];
}
}
}
return roman;
}</lang>
Most straightforward (nothing elegant about it, but it's simple, and can calcuate output length) <lang C>#include <stdio.h>
int to_roman(char *out, int n) {
int len = 0;
if (n <= 0) return 0; /* error indication */
- define RPUT(c) if (out) out[len] = c; len++
while(n>= 1000) { n -= 1000;RPUT('M'); };
if (n >= 900) { n -= 900; RPUT('C'); RPUT('M'); };
if (n >= 500) { n -= 500; RPUT('D'); };
if (n >= 400) { n -= 400; RPUT('C'); RPUT('D'); };
while (n >= 100){ n -= 100; RPUT('C'); };
if (n >= 90) { n -= 90; RPUT('X'); RPUT('C'); };
if (n >= 50) { n -= 50; RPUT('L'); };
if (n >= 40) { n -= 40; RPUT('X'); RPUT('L'); };
while (n >= 10) { n -= 10; RPUT('X'); };
if (n >= 9) { n -= 9; RPUT('I'); RPUT('X'); };
if (n >= 5) { n -= 5; RPUT('V'); };
if (n >= 4) { n -= 4; RPUT('I'); RPUT('V'); };
while (n) { n--; RPUT('I'); };
RPUT('\0');
- undef RPUT
return len;
}
int main() {
char buf[16];
int d = to_roman(buf, 1666);
printf("roman for 1666 is %d bytes: %s\n", d, buf);
d = 68999123;
printf("%d would have required %d bytes\n", d, to_roman(0, d));
return 0;
}</lang>Output:
roman for 1666 is 8 bytes: MDCLXVI 68999123 would have required 69006 bytes
C#
<lang csharp>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));
}
}
}</lang>
Output:
1 = I 2 = II 4 = IV 8 = VIII 16 = XVI 32 = XXXII 64 = LXIV 128 = CXXVIII 256 = CCLVI 512 = DXII 1024 = MXXIV
C++
<lang cpp>#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;
}
}</lang>
Clojure
The easiest way is to use the built-in cl-format function <lang Clojure>(def arabic->roman
(partial clojure.pprint/cl-format nil "~@R"))
(arabic->roman 147)
- "CXXIII"
(arabic->roman 99)
- "XCIX"</lang>
Alternatively:
<lang Clojure>(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"</lang>
An alternate implementation:
<lang Clojure> (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)))))))))
</lang>
Usage:
<lang Clojure> (a2r 1666) "MDCLXVI"
(map a2r [1000 1 389 45]) ("M" "I" "CCCLXXXIX" "XLV") </lang>
COBOL
<lang 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
.
</lang>
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
<lang 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"
</lang>
Common Lisp
<lang lisp>(defun roman-numeral (n)
(format nil "~@R" n))</lang>
D
<lang 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() {}</lang>
Delphi
<lang delphi>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.</lang>
DWScript
<lang delphi>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));</lang>
ECL
<lang 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</lang>
Eiffel
<lang 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</lang>
Emacs Lisp
<lang lisp> (defun ar2ro (AN)
"translate from arabic number AN to roman number, 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)))
</lang>
Erlang
<lang erlang>-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].</lang>
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: <lang erlang> -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}]. </lang>
- 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"
Euphoria
<lang Euphoria>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)})</lang>
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: <lang Excel> =ROMAN(2013,0) </lang>
It becomes: <lang> MMXIII </lang>
F#
<lang fsharp>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</lang>
Output
MCMXC MMVIII MDCLXVI
Factor
A roman numeral library ships with Factor. <lang factor>USE: roman ( scratchpad ) 3333 >roman . "mmmcccxxxiii"</lang>
Parts of the implementation:
<lang factor>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 ;</lang>
FALSE
<lang 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"]#%</lang>
Fan
<lang 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)}") }
}
}</lang>
Forth
<lang 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</lang>
Alternative implementation <lang forth>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</lang>
Fortran
<lang fortran>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</lang>
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...) <lang go>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")
}
}
}</lang> Output:
1990 == MCMXC 2008 == MMVIII 1666 == MDCLXVI
Groovy
<lang 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'</lang>
Haskell
With an explicit decimal digit representation list:
<lang haskell>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</lang>
Output:
<lang haskell>*Main> map toRoman [1999,25,944] ["MCMXCIX","XXV","CMXLIV"]</lang>
HicEst
<lang 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</lang>
Icon and Unicon
<lang Icon>link numbers # commas, roman
procedure main(arglist) every x := !arglist do
write(commas(x), " -> ",roman(x)|"*** can't convert to Roman numerals ***")
end</lang>
numbers.icn provides roman as seen below and is based upon a James Gimple SNOBOL4 function.
<lang Icon>procedure roman(n) #: convert integer to Roman numeral
local arabic, result static equiv
initial equiv := ["","I","II","III","IV","V","VI","VII","VIII","IX"]
integer(n) > 0 | fail
result := ""
every arabic := !n do
result := map(result,"IVXLCDM","XLCDM**") || equiv[arabic + 1]
if find("*",result) then fail else return result
end</lang>
Sample output:
#roman.exe 3 4 8 49 2010 1666 3000 3999 4000 3 -> III 4 -> IV 8 -> VIII 49 -> XLIX 2,010 -> MMX 1,666 -> MDCLXVI 3,999 -> MMMCMXCIX 4,000 -> *** can't convert to Roman numerals ***
Io
<lang Io>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</lang>
J
rfd obtains Roman numerals from decimals.
<lang j>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&|</lang>
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:<lang j> rfd 1234 MCCXXXIV
rfd 567
DLXVII
rfd 89
LXXXIX</lang>
Derived from the J Wiki. Further examples of use will be found there.
Java
The conversion function throws an IllegalArgumentException for non-positive numbers, since Java does not have unsigned primitives.
<lang java5>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);
}
}</lang> 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)
<lang java5>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);
}
}</lang> Output:
1999 = MCMXCIX MCMXCIX = 1999 25 = XXV XXV = 25 944 = CMXLIV CMXLIV = 944
JavaScript
<lang javascript>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"</lang>
Lasso
<lang 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)</lang>
LaTeX
The macro \Roman is defined for uppercase roman numeral, accepting as argument a name of an existing counter.
<lang latex>\documentclass{article} \begin{document} \newcounter{currentyear}\setcounter{currentyear}{\year} Anno Domini \Roman{currentyear} \end{document}</lang>
Liberty BASIC
<lang lb>
dim arabic( 12)
for i =0 to 12
read k
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 </lang>
2009 MMIX 1666 MDCLXVI 3888 MMMDCCCLXXXVIII
Logo
<lang 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</lang>
<lang 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</lang>
LotusScript
<lang lss> 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
</lang>
Lua
<lang 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()</lang>
M4
<lang 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)</lang>
Output:
MMMDCLXXV
Maple
<lang Maple>> for n in [ 1666, 1990, 2008 ] do printf( "%d\t%s\n", n, convert( n, 'roman' ) ) end: 1666 MDCLXVI 1990 MCMXC 2008 MMVIII</lang>
Mathematica
Define a custom function that works on positive numbers (RomanForm[0] will not be evaluated): <lang Mathematica>RomanForm[i_Integer?Positive] :=
Module[{num = i, string = "", value, letters, digits},
digits = {{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[num > 0, {value, letters} =
Which @@ Flatten[{num >= #1, ##} & /@ digits, 1];
num -= value;
string = string <> letters;];
string]</lang>
Examples: <lang Mathematica>RomanForm[4] RomanForm[99] RomanForm[1337] RomanForm[1666] RomanForm[6889]</lang> gives back: <lang Mathematica>IV XCIX MCCCXXXVII MDCLXVI MMMMMMDCCCLXXXIX</lang>
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/1is 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 '1' is removed and the function is recursively called with [] (the empty list)..
- 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 '2' is removed and the function is recursively called with ['1'].
- 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
<lang Mercury>
- - 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.
</lang>
Usage and 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:
<lang Mercury>
- - 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.
</lang>
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.
MUMPS
<lang 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</lang>
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 <lang MUMPS>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</lang>
Nimrod
<lang nimrod>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(x): string =
var x = x result = "" for a,r in items(nums): result.add(repeatStr(x div a, r)) x = x 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 toRoman(i)</lang>
Objeck
<lang objeck> 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();
}
}
} </lang>
OCaml
With an explicit decimal digit representation list:
<lang ocaml>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</lang>
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']
OpenEdge/Progress
<lang 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. </lang> Output:
--------------------------- Message (Press HELP to view stack trace) --------------------------- 1990 MCMXC 2008 MMVIII 2000 MM 1666 MDCLXVI --------------------------- OK Help ---------------------------
Oz
<lang oz>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}</lang>
PARI/GP
Old-style Roman numerals <lang parigp>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()
};</lang>
This simple version of medieval Roman numerals does not handle large numbers. <lang parigp>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()
};</lang>
Pascal
See Delphi
Perl
Simple program
Simple, fast, produces same output as the Math::Roman module and the Perl 6 example, less crazy than writing a Latin program, and doesn't require experimental modules like the Perl 6 translation. <lang perl>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;
}
say roman($_) for 1..2012;</lang>
Using a module
<lang perl>use Math::Roman qw/roman/; say roman($_) for 1..2012'</lang>
Using Perligata, a module to write programs in Latin
Perligata outputs numbers in Arabic, but the verb come ("beautify") may be used to convert numbers to proper Roman numerals:
<lang perl>per quisque in I tum C conscribementum sic
hoc tum duos multiplicamentum comementum egresso scribe.
cis</lang>
Ported version of Perl6
<lang perl>use v5.12; use Sub::SmartMatch; use SmartMatch::Sugar qw(any); 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
);
multi roman => [0], sub { }; multi roman => any, sub {
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);
}
};
say roman($_) for 1..2_012;</lang>
Perl 6
<lang perl6>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);
}
}</lang>
Sample usage
<lang perl6>for 1 .. 2_010 -> $x {
say roman($x);
}</lang>
PHP
<lang php> /**
* 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; } </lang>
PicoLisp
<lang 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) ) ) ) )</lang>
Output:
: (roman 1009) -> "MIX" : (roman 1666) -> "MDCLXVI"
Pike
<lang pike>import String; int main(){
write(int2roman(2009) + "\n"); write(int2roman(1666) + "\n"); write(int2roman(1337) + "\n");
}</lang>
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.
<lang tex>\def\upperroman#1{\uppercase\expandafter{\romannumeral#1}} Anno Domini \upperroman{\year} \bye</lang>
PL/I
<lang 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; </lang> Results:
11 XI 1990 MCMXC 2008 MMVIII 1666 MDCLXVI 1999 MCMXCIX
PL/SQL
<lang 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. */
DECLARE FUNCTION rencode(an IN NUMBER) RETURN VARCHAR2 IS
rs VARCHAR2(20);
BEGIN SELECT to_char(to_char(to_date(an,'YYYY'), 'RRRR'), 'RN') INTO rs FROM dual; RETURN rs; END;
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; </lang>
PowerBASIC
<lang powerbasic>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</lang>
Prolog
Works with SWI-Prolog and library clpfd.
Library clpfd assures that the program works in both managements : Roman towards Arabic and Arabic towards Roman.
<lang Prolog>:- 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]). </lang> 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 .
Protium
Roman numbers are built in to Protium as a particular form of national number. However, for the sake of the task the _RO opcode has been defined. <lang html><@ DEFUDOLITLIT>_RO|__Transformer|<@ DEFKEYPAR>__NationalNumericID|2</@><@ LETRESCS%NNMPAR>...|1</@></@>
<@ ENU$$DLSTLITLIT>1990,2008,1,2,64,124,1666,10001|,| <@ SAYELTLST>...</@> is <@ SAY_ROELTLSTLIT>...|RomanLowerUnicode</@> <@ SAY_ROELTLSTLIT>...|RomanUpperUnicode</@> <@ SAY_ROELTLSTLIT>...|RomanASCII</@> </@></lang>
Same code in padded-out, variable-length English dialect <lang html><# 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</#> </#></lang>
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
PureBasic
<lang 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</lang>
Python
<lang python>roman = "MDCLXVmdclxvi"; # UPPERCASE for thousands # adjust_roman = "CCXXmmccxxii"; 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:
org -= -adjust_arabic[scale] + arabic_scale;
out += adjust_roman[scale] + roman[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))</lang>
An alternative which uses the divmod() function<lang python>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]</lang>
It is more Pythonic to use zip to iterate over two lists together: <lang python>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))
</lang>
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.
<lang R>as.roman(1666) # MDCLXVI</lang>
Since the object as.roman creates is just an integer vector with a class, you can do arithmetic with Roman numerals:
<lang R>as.roman(1666) + 334 # MM</lang>
Racket
Straight recursion: <lang Racket>#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 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 "")))</lang>
Using for/fold and quotient/remainder to remove repetition: <lang Racket>#lang racket (define (number->list n)
(for/fold ([result null])
([decimal '(1000 900 500 400 100 90 50 40 10 5 4 1)]
[roman '(M CM D CD C XC L XL X 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)))</lang>
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.
<lang Retro>
- 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 ;
</lang>
REXX
version 1
<lang rexx>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</lang>
version 2
This version of a REXX program allows almost any non-negative (whole) decimal number.
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:
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 code was ripped out of my general routine that also supported versions for Attic, ancient Roman, and modern Roman numerals.)
The code is bulkier than most at it deals with any non-negative decimal number, and more boilerplate code is(was) present to handle the above versions.
<lang rexx>/*REXX program converts (Arabic) decimal numbers (≥0) ──► Roman numerals*/
numeric digits 10000 /*could be higher if wanted*/
parse arg nums
if nums= then do /*not specified? Gen some.*/
do j=0 by 11 to 111
nums=nums j
end /*j*/
nums=nums 49
do k=88 by 100 to 1200
nums=nums k
end /*k*/
nums=nums 1000 2000 3000 4000 5000 6000
do m=88 by 200 to 1200
nums=nums m
end /*m*/
nums=nums 1304 1405 1506 1607 1708 1809 1910 2011
do p=4 to 50 /*there is no limit to this*/
nums=nums 10**p
end /*p*/
end /*end generation of numbers*/
do i=1 for words(nums); x=word(nums,i)
say right(x,55) dec2rom(x)
end /*i*/
exit /*stick a fork in it, we're done.*/ /*───────────────────────────DEC2ROM subroutine─────────────────────────*/ dec2rom: procedure; parse arg n,# /*get number, assign # to a null. */ n=space(translate(n,,','),0) /*remove any commas from number. */ 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 parens to use.*/ highPos=(maxnp+1)*3 /*highest position of number. */ nn=reverse(right(n,highPos,0)) /*digits for Arabic───►Roman conv.*/ nine=9 four=4; do j=highPos to 1 by -3
_=substr(nn,j,1); select
when _==nine then hx='CM'
when _>= 5 then hx='D'copies("C",_-5)
when _==four then hx='CD'
otherwise hx=copies('C',_)
end
_=substr(nn,j-1,1); select
when _==nine then tx='XC'
when _>= 5 then tx='L'copies("X",_-5)
when _==four then tx='XL'
otherwise tx=copies('X',_)
end
_=substr(nn,j-2,1); select
when _==nine then ux='IX'
when _>= 5 then ux='V'copies("I",_-5)
when _==four then ux='IV'
otherwise ux=copies('I',_)
end
xx=hx || tx || ux
if xx\== then #=# ||copies('(',(j-1)%3)xx ||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 #</lang>
Some older REXXes don't have a changestr BIF, so one is included here ──► CHANGESTR.REX.
output when using the default input (within the REXX program):
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))))))))))))))))
Ruby
Roman numeral generation was used as an example for demonstrating Test Driven Development in Ruby. The solution came to be: <lang ruby>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</lang>
- Output:
1990 => MCMXC 2008 => MMVIII 1666 => MDCLXVI
Another shorter version if we don't consider calculating the substractors:
<lang ruby> 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 </lang>
Yet another way to solve it in terms of reduce
<lang ruby> 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 </lang>
Run BASIC
<lang runbasic>[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</lang>
Rust
<lang rust>struct RomanNumeral {
symbol: &'static str, value: uint
}
static 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(num: uint) -> String {
for numeral in NUMERALS.iter() {
if num >= numeral.value {
return numeral.symbol.to_string() + to_roman(num - numeral.value);
}
}
return "".to_string();
}
fn main() {
let nums = [2014, 1999, 25, 1666, 3888];
for n in nums.iter() {
println!("{:u} = {:s}", *n, to_roman(*n));
}
}</lang>
- Output:
2014 = MMXIV 1999 = MCMXCIX 25 = XXV 1666 = MDCLXVI 3888 = MMMDCCCLXXXVIII
Scala
<lang scala>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 => ""
}</lang>
Sample:
scala> List(1990, 2008, 1666) map toRoman res55: List[String] = List(MCMXC, MMVIII, MDCLXVI)
Scala Using foldLeft
<lang Scala>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)</lang>
Same implementation, different code-style:
<lang Scala>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)
}
}
}</lang>
- Output:
1990 => MCMXC 2008 => MMVIII 1666 => MDCLXVI
Scheme
This uses format directives supported in Chez Scheme since v6.9b; YMMV.
<lang scheme>(define (to-roman n)
(format "~@r" n))</lang>
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.
<lang seed7>$ 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;</lang>
Original source [1].
Sidef
<lang ruby>func arabic2roman(num, roman=) {
const 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));</lang>
- Output:
1990 in roman is MCMXC 2008 in roman is MMVIII 1666 in roman is MDCLXVI
Smalltalk
in ST/X, integers already know how to print themselves as roman number: <lang smalltalk>2013 printRomanOn:Stdout naive:false</lang>
outputs:
MMXIII
the implementation is: <lang smalltalk> 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] ].
].
</lang>
SNOBOL4
Adapted from Catspaw SNOBOL Tutorial, Chapter 6
<lang snobol4>
- 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</lang> Outputs:
1999 = MCMXCIX 24 = XXIV 944 = CMXLIV
Here's a non-recursive version, and a Roman-to-Arabic converter to boot.
<lang SNOBOL4>* # 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</lang>
Output:
2010=MMX 1999=MCMXCIX 1492=MCDXCII 1066=MLXVI 476=CDLXXVI MMX=2010 MCMXCIX=1999 MCDXCII=1492 MLXVI=1066 CDLXXVI=476
SQL
<lang SQL> -- -- This only works under Oracle and has the limitation of 1 to 3999 --- Higher numbers in the Middle Ages were represented by "superscores" on top of the numeral to multiply by 1000 --- Vertical bars to the sides multiply by 100. So |M| means 100,000 -- When the query is run, user provides the Arabic numerals for the ar_year -- A.Kebedjiev --
SELECT to_char(to_char(to_date(&ar_year,'YYYY'), 'RRRR'), 'RN') AS roman_year FROM DUAL;
-- or you can type in the year directly
SELECT to_char(to_char(to_date(1666,'YYYY'), 'RRRR'), 'RN') AS roman_year FROM DUAL;
ROMAN_YEAR MDCLXVI
</lang>
Swift
<lang swift>func arabicToRoman(n: Int) -> String {
var x = n
var str = ""
for (value, letter) in [(1000, "M"),
( 900, "CM"),
( 500, "D"),
( 100, "C"),
( 90, "XC"),
( 50, "L"),
( 10, "X"),
( 9, "IX"),
( 5, "V"),
( 1, "I")] {
while x >= value {
str += letter
x -= value
}
}
return str
}</lang>
Tcl
<lang 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
}</lang>
TI-83 BASIC
<lang ti83b>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
</lang>
TUSCRIPT
<lang tuscript> $$ MODE TUSCRIPT LOOP arab_number="1990'2008'1666" roman_number = ENCODE (arab_number,ROMAN) PRINT "Arabic number ",arab_number, " equals ", roman_number ENDLOOP </lang> Output:
Arabic number 1990 equals MCMXC Arabic number 2008 equals MMVIII Arabic number 1666 equals MDCLXVI
uBasic/4tH
<lang>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, : Push 1999 : GoSub _FNroman Print 2014, : Push 2014 : GoSub _FNroman Print 1666, : Push 1666 : GoSub _FNroman Print 3888, : Push 3888 : GoSub _FNroman
End
_FNroman ' ( n --)
Local (1) ' Define a@
' Try all numbers in array
For a@ = 12 To 0 Step -1
Do While Tos() > @(a@) - 1 ' Several occurences of same number?
GoSub ((a@ + 1) * 10) ' Print roman digit
Push Pop() - @(a@) ' Decrement number
Loop
Next
Print : a@ = Pop() ' Terminate line and clear stack
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</lang>
UNIX Shell
<lang bash>roman() {
local values=( 1000 900 500 400 100 90 50 40 10 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</lang>
- Output:
1999 = MCMXCVIV 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. <lang Ursala>#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>+-</lang>
This test program applies the function to each member of a list of numbers. <lang Ursala>#show+
test = roman* <1990,2008,1,2,64,124,1666,10001></lang> output:
MCMXC MMVIII I II LXIV CXXIV MDCLXVI MMMMMMMMMMI
Vedit macro language
<lang vedit>// 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</lang>
Output:
4 = IV 12 = XII 1666 = MDCLXVI 1990 = MCMXC 2011 = MMXI
Visual Basic
<lang vb>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()
MsgBox toRoman(Val(InputBox("Number, please")))
End Sub</lang>
XSLT
<lang 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 > /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 < $stop">
<xsl:call-template name="for">
<xsl:with-param name="stop">
<xsl:value-of select="$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> </lang>
zkl
<lang zkl>var 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) { z := i / N; text += R * z; i = i%N; }
return(text);
}</lang>
toRoman(1990) //-->"MCMXC" toRoman(2008) //-->"MMVIII" toRoman(1666) //-->"MDCLXVI"
Zsh
Based on the python solution. <lang zsh>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
}</lang>
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