Loops/While
Start an integer value at 1024.
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
Loop while it is greater than zero.
Print the value (with a newline) and divide it by two each time through the loop.
- Related tasks
- Loop over multiple arrays simultaneously
- Loops/Break
- Loops/Continue
- Loops/Do-while
- Loops/Downward for
- Loops/For
- Loops/For with a specified step
- Loops/Foreach
- Loops/Increment loop index within loop body
- Loops/Infinite
- Loops/N plus one half
- Loops/Nested
- Loops/While
- Loops/with multiple ranges
- Loops/Wrong ranges
0815
<:400:~}:_:%<:a:~$=<:2:=/^:_:
11l
V n = 1024
L n > 0
print(n)
n I/= 2
360 Assembly
- Basic
Using binary arithmetic. Convert results to EBCDIC printable output.
* While 27/06/2016
WHILELOO CSECT program's control section
USING WHILELOO,12 set base register
LR 12,15 load base register
LA 6,1024 v=1024
LOOP LTR 6,6 while v>0
BNP ENDLOOP .
CVD 6,PACKED convert v to packed decimal
OI PACKED+7,X'0F' prepare unpack
UNPK WTOTXT,PACKED packed decimal to zoned printable
WTO MF=(E,WTOMSG) display v
SRA 6,1 v=v/2 by right shift
B LOOP end while
ENDLOOP BR 14 return to caller
PACKED DS PL8 packed decimal
WTOMSG DS 0F full word alignment for wto
WTOLEN DC AL2(8),H'0' length of wto buffer (4+1)
WTOTXT DC CL4' ' wto text
END WHILELOO
- Output:
(+ sign indicates "problem state" (non system key) issued WTO's
+1024 +0512 +0256 +0128 +0064 +0032 +0016 +0008 +0004 +0002 +0001
- Structured Macros
* While 27/06/2016
WHILELOO CSECT
USING WHILELOO,12 set base register
LR 12,15 load base register
LA 6,1024 v=1024
DO WHILE=(LTR,6,P,6) do while v>0
CVD 6,PACKED convert v to packed decimal
OI PACKED+7,X'0F' prepare unpack
UNPK WTOTXT,PACKED packed decimal to zoned printable
WTO MF=(E,WTOMSG) display
SRA 6,1 v=v/2 by right shift
ENDDO , end while
BR 14 return to caller
PACKED DS PL8 packed decimal
WTOMSG DS 0F full word alignment for wto
WTOLEN DC AL2(8),H'0' length of wto buffer (4+1)
WTOTXT DC CL4' ' wto text
END WHILELOO
- Output:
Same as above
6502 Assembly
Code is called as a subroutine (i.e. JSR LoopsWhile). Specific OS/hardware routines for printing are left unimplemented.
LoopsWhile: PHA ;push accumulator onto stack
LDA #$00 ;the 6502 is an 8-bit processor
STA Ilow ;and so 1024 ($0400) must be stored in two memory locations
LDA #$04
STA Ihigh
WhileLoop: LDA Ilow
BNE NotZero
LDA Ihigh
BEQ EndLoop
NotZero: JSR PrintI ;routine not implemented
LSR Ihigh ;shift right
ROR Ilow ;rotate right
JMP WhileLoop
EndLoop: PLA ;restore accumulator from stack
RTS ;return from subroutine
68000 Assembly
Printing routines are left out since this is not the focus of the task.
main:
MOVE.W #1024,D0
WhileLoop:
jsr PrintHexWord
LSR.W #1,D0
BNE WhileLoop
AArch64 Assembly
/* ARM assembly AARCH64 Raspberry PI 3B */
/* program loopwhile64.s */
/*******************************************/
/* Constantes file */
/*******************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
/*********************************/
/* Initialized data */
/*********************************/
.data
szMessResult: .asciz "@" // message result
szCarriageReturn: .asciz "\n"
/*********************************/
/* UnInitialized data */
/*********************************/
.bss
sZoneConv: .skip 24
/*********************************/
/* code section */
/*********************************/
.text
.global main
main: // entry of program
mov x20,#1024 // loop counter
1: // begin loop
mov x0,x20
ldr x1,qAdrsZoneConv // display value
bl conversion10 // decimal conversion
ldr x0,qAdrszMessResult
ldr x1,qAdrsZoneConv
bl strInsertAtCharInc // insert result at @ character
bl affichageMess // display message
ldr x0,qAdrszCarriageReturn
bl affichageMess // display return line
lsr x20,x20,1 // division by 2
cmp x20,0 // end ?
bgt 1b // no ->begin loop one
100: // standard end of the program
mov x0,0 // return code
mov x8,EXIT // request to exit program
svc 0 // perform the system call
qAdrsZoneConv: .quad sZoneConv
qAdrszMessResult: .quad szMessResult
qAdrszCarriageReturn: .quad szCarriageReturn
/********************************************************/
/* File Include fonctions */
/********************************************************/
/* for this file see task include a file in language AArch64 assembly */
.include "../includeARM64.inc"
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Action!
PROC Main()
CARD i=[1024]
WHILE i>0
DO
PrintCE(i)
i=i/2
OD
RETURN
- Output:
Screenshot from Atari 8-bit computer
1024 512 256 128 64 32 16 8 4 2 1
ActionScript
var i:int = 1024;
while (i > 0) {
trace(i);
i /= 2;
}
Ada
declare
I : Integer := 1024;
begin
while I > 0 loop
Put_Line(Integer'Image(I));
I := I / 2;
end loop;
end;
Agena
Tested with Agena 2.9.5 Win32
scope
local i := 1024;
while i > 0 do
print( i );
i := i \ 2
od
epocs
Aime
integer i;
i = 1024;
while (i) {
o_plan(i, "\n");
i /= 2;
}
ALGOL 60
The Loops/While structure was in the Algol 60 report of January 1963.
begin
comment Loops/While - algol60 - 21/10/2014;
integer i;
for i:=1024,i div 2 while i>0 do outinteger(1,i)
end
- Output:
1024 512 256 128 64 32 16 8 4 2 1
ALGOL 68
INT i := 1024;
WHILE i > 0 DO
print(i);
i := i OVER 2
OD
- Output:
+1024 +512 +256 +128 +64 +32 +16 +8 +4 +2 +1
ALGOL W
begin
integer i;
i := 1024;
while i > 0 do
begin
write( i );
i := i div 2
end
end.
ALGOL-M
begin
integer i;
i := 1024;
while i > 0 do begin
write( i );
i := i / 2;
end;
end
Amazing Hopper
#include <jambo.h>
Main
i=1024
Loop
Printnl 'i'
i \= 2
Back if 'i' is positive
End
Assembler Hopper code:
main:
i=1024
____CODE_JUMP____883612951:,
{i};{"\n"}print;
i\=2
{i},jpos(____CODE_JUMP____883612951),____CODE_JUMP____854411479:,
emptystack?do{{0}};return
- Output:
1024 512 256 128 64 32 16 8 4 2 1
AmbientTalk
Note: in AmbientTalk, while:do: is a keyworded message (as in Smalltalk). Both arguments to this message must be blocks (aka anonymous functions or thunks).
// print 1024 512 etc
def i := 1024;
while: { i > 0 } do: {
system.print(" "+i);
i := i/2;
}
AmigaE
PROC main()
DEF i = 1024
WHILE i > 0
WriteF('\d\n', i)
i := i / 2
ENDWHILE
ENDPROC
AppleScript
AppleScript does not natively support a standard out. Use the Script Editor's Event Log as the output.
set i to 1024
repeat while i > 0
log i
set i to i / 2
end repeat
ARM Assembly
/* ARM assembly Raspberry PI */
/* program loopwhile.s */
/* Constantes */
.equ STDOUT, 1 @ Linux output console
.equ EXIT, 1 @ Linux syscall
.equ WRITE, 4 @ Linux syscall
/*********************************/
/* Initialized data */
/*********************************/
.data
szMessResult: .ascii "" @ message result
sMessValeur: .fill 11, 1, ' '
szCarriageReturn: .asciz "\n"
/*********************************/
/* UnInitialized data */
/*********************************/
.bss
/*********************************/
/* code section */
/*********************************/
.text
.global main
main: @ entry of program
mov r4,#1024 @ loop counter
1: @ begin loop
mov r0,r4
ldr r1,iAdrsMessValeur @ display value
bl conversion10 @ decimal conversion
ldr r0,iAdrszMessResult
bl affichageMess @ display message
ldr r0,iAdrszCarriageReturn
bl affichageMess @ display return line
lsr r4,#1 @ division by 2
cmp r4,#0 @ end ?
bgt 1b @ no ->begin loop one
100: @ standard end of the program
mov r0, #0 @ return code
mov r7, #EXIT @ request to exit program
svc #0 @ perform the system call
iAdrsMessValeur: .int sMessValeur
iAdrszMessResult: .int szMessResult
iAdrszCarriageReturn: .int szCarriageReturn
/******************************************************************/
/* display text with size calculation */
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
push {r0,r1,r2,r7,lr} @ save registres
mov r2,#0 @ counter length
1: @ loop length calculation
ldrb r1,[r0,r2] @ read octet start position + index
cmp r1,#0 @ if 0 its over
addne r2,r2,#1 @ else add 1 in the length
bne 1b @ and loop
@ so here r2 contains the length of the message
mov r1,r0 @ address message in r1
mov r0,#STDOUT @ code to write to the standard output Linux
mov r7, #WRITE @ code call system "write"
svc #0 @ call systeme
pop {r0,r1,r2,r7,lr} @ restaur registers */
bx lr @ return
/******************************************************************/
/* Converting a register to a decimal */
/******************************************************************/
/* r0 contains value and r1 address area */
.equ LGZONECAL, 10
conversion10:
push {r1-r4,lr} @ save registers
mov r3,r1
mov r2,#LGZONECAL
1: @ start loop
bl divisionpar10 @ r0 <- dividende. quotient ->r0 reste -> r1
add r1,#48 @ digit
strb r1,[r3,r2] @ store digit on area
cmp r0,#0 @ stop if quotient = 0
subne r2,#1 @ previous position
bne 1b @ else loop
@ end replaces digit in front of area
mov r4,#0
2:
ldrb r1,[r3,r2]
strb r1,[r3,r4] @ store in area begin
add r4,#1
add r2,#1 @ previous position
cmp r2,#LGZONECAL @ end
ble 2b @ loop
mov r1,#0 @ final zero
strb r1,[r3,r4]
100:
pop {r1-r4,lr} @ restaur registres
bx lr @return
/***************************************************/
/* division par 10 signé */
/* Thanks to http://thinkingeek.com/arm-assembler-raspberry-pi/*
/* and http://www.hackersdelight.org/ */
/***************************************************/
/* r0 dividende */
/* r0 quotient */
/* r1 remainder */
divisionpar10:
/* r0 contains the argument to be divided by 10 */
push {r2-r4} @ save registers */
mov r4,r0
mov r3,#0x6667 @ r3 <- magic_number lower
movt r3,#0x6666 @ r3 <- magic_number upper
smull r1, r2, r3, r0 @ r1 <- Lower32Bits(r1*r0). r2 <- Upper32Bits(r1*r0)
mov r2, r2, ASR #2 @ r2 <- r2 >> 2
mov r1, r0, LSR #31 @ r1 <- r0 >> 31
add r0, r2, r1 @ r0 <- r2 + r1
add r2,r0,r0, lsl #2 @ r2 <- r0 * 5
sub r1,r4,r2, lsl #1 @ r1 <- r4 - (r2 * 2) = r4 - (r0 * 10)
pop {r2-r4}
bx lr @ return
ArnoldC
IT'S SHOWTIME
HEY CHRISTMAS TREE n
YOU SET US UP 1024
STICK AROUND n
TALK TO THE HAND n
GET TO THE CHOPPER n
HERE IS MY INVITATION n
HE HAD TO SPLIT 2
ENOUGH TALK
CHILL
YOU HAVE BEEN TERMINATED
Arturo
i: 1024
while [i>0] [
print i
i: i/2
]
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Asymptote
int i = 1024;
while(i > 0) {
write(i);
i = i # 2; //or also i = quotient(i, 2);
}
//# Integer division; equivalent to quotient(x,y).
//Noting that the Python3 community adopted the comment symbol (//) for integer division, the
//Asymptote community decided to reciprocate and use their comment symbol for integer division!
ATS
With compile-time proof of termination of the loop (which is really a tail recursion).
#include "share/atspre_staload.hats"
fn
loop_while () : void =
let
fun
loop {n : int | 0 <= n} .<n>.
(n : uint n) : void =
if n <> 0U then
begin
println! (n);
loop (n / 2U)
end
in
loop 1024U
end
implement
main0 () =
loop_while ()
- Output:
1024 512 256 128 64 32 16 8 4 2 1
It is also possible to write an actual ‘while’ loop, although this method requires a variable (the ‘var’ declaration below) and has other problems, and should be used sparingly.
#include "share/atspre_staload.hats"
fn
loop_while () : void =
let
var n : uint = 1024U
in
while (0U < n)
begin
println! (n);
n := n / 2U
end
end
implement
main0 () =
loop_while ()
AutoHotkey
i = 1024
While (i > 0)
{
output = %output%`n%i%
i := Floor(i / 2)
}
MsgBox % output
AWK
BEGIN {
v = 1024
while(v > 0) {
print v
v = int(v/2)
}
}
Axe
1024→A
While A>0
Disp A▶Dec,i
A/2→A
End
Bait
fun main() {
mut i := 1024
for i > 0 {
println(i)
i = i / 2
}
}
BASIC
In general, the WHILE
-WEND
(or DO WHILE
-LOOP
) statement is used or it is simulated with a construct with conditional jump.
ANSI BASIC
100 LET I = 1024
110 DO WHILE I > 0
120 PRINT I
130 LET I = INT(I / 2)
140 LOOP
150 END
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Applesoft BASIC
10 I% = 1024
20 IF I% > 0 THEN PRINT I%:I% = I% / 2: GOTO 20
ASIC
REM Loops/While
I = 1024
WHILE I > 0
PRINT I
I = I / 2
WEND
END
- Output:
1024 512 256 128 64 32 16 8 4 2 1
BaCon
i = 1024
WHILE i > 0
PRINT i
i = i / 2
WEND
Ballerina
int i = 1024;
while i > 0 {
io:println(i);
i = i / 2;
}
BASIC256
i = 1024
while i > 0
print i
i = i \ 2
end while
end
BBC BASIC
i% = 1024
WHILE i%
PRINT i%
i% DIV= 2
ENDWHILE
Chipmunk Basic
Both loops are equivalent
100 i = 1024
110 do while i > 0
120 print i
130 i = int(i/2)
140 loop
150 print
160 i = 1024
170 while i > 0
180 print i
190 i = int(i/2)
200 wend
Commodore BASIC
There is no WHILE construct in Commodore BASIC. A GOTO construct is used instead. Also, an integer variable name has a % sign as its suffix.
10 N% = 1024
20 IF N% = 0 THEN 60
30 PRINT N%
40 N% = N%/2
50 GOTO 20
60 END
- Output:
1024 512 256 128 64 32 16 8 4 2 1
See also Minimal BASIC
Creative Basic
DEF X:INT
X=1024
OPENCONSOLE
WHILE X>0
PRINT X
X=X/2
ENDWHILE
'Output starts with 1024 and ends with 1.
'Putting the following in the loop will produce output starting with 512 and ending with 0:
'X=X/2
'PRINT X
PRINT:PRINT"Press any key to end."
'Keep console from closing right away so the figures can be read.
WHILE INKEY$="":ENDWHILE
CLOSECONSOLE
'Since this is, in fact, a Creative Basic console program.
END
Note: Spacing is not an issue. I just find the code to be more readable with spaces.
FreeBASIC
' FB 1.05.0 Win64
Dim i As Integer = 1024
While i > 0
Print i
i Shr= 1
Wend
Sleep
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Gambas
Click this link to run this code
Public Sub Main()
Dim siCount As Short = 1024
While siCount > 0
Print siCount;;
siCount /= 2
Wend
End
Output:
1024 512 256 128 64 32 16 8 4 2 1
GW-BASIC
10 I = 1024
20 WHILE I > 0
30 PRINT I
40 i = INT(i/2)
50 WEND
60 END
IS-BASIC
100 LET I=1024
110 DO WHILE I>0
120 PRINT I
130 LET I=IP(I/2)
140 LOOP
IWBASIC
DEF X:INT
X=1024
OPENCONSOLE
WHILE X>0
PRINT X
X=X/2
ENDWHILE
'Output starts with 1024 and ends with 1.
'Putting the following in the loop will produce output starting with 512 and ending with 0:
'X=X/2
'PRINT X
'When compiled as a console only program, a press any key to continue message is automatic.
'I presume code is added by the compiler.
CLOSECONSOLE
'Since this is, in fact, an IWBASIC console program, which compiles and runs.
END
Note: Spacing is not an issue. I just find the code to be more readable with spaces.
Liberty BASIC
All integers are changed to floats if an operation creates a non-integer result. Without using int() the program keeps going until erroring because accuracy was lost.
i = 1024
while i > 0
print i
i = int( i / 2)
wend
end
Microsoft Small Basic
i = 1024
While i > 0
TextWindow.WriteLine(i)
i = Math.Floor(i / 2)
EndWhile
Minimal BASIC
Minimal BASIC have no while
construct. Equivalent using conditional jump:
10 REM Loops/While
20 LET I = 1024
40 IF I <= 0 THEN 80
50 PRINT I
60 LET I = INT(I/2)
70 GOTO 40
80 END
MSX Basic
There is no WHILE
construct in MSX Basic. A GOTO
construct is used instead.
10 I% = 1024
20 IF I% = 0 THEN END
30 PRINT I%
40 I% = I%/2 : rem INT(I/2)
50 GOTO 20
Solutions GW-BASIC and Minimal BASIC work without changes.
Nascom BASIC
See Minimal BASIC.
If the repeated sequence is short then the loop can be written in one line.
10 REM Loops/While
20 LET I=1024
30 IF I>0 THEN PRINT I:I=INT(I/2):GOTO 30
40 END
NS-HUBASIC
10 I=1024
20 IF I=0 THEN END
30 PRINT I
40 I=I/2
50 GOTO 20
PureBasic
If OpenConsole()
x.i = 1024
While x > 0
PrintN(Str(x))
x / 2
Wend
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit")
Input()
CloseConsole()
EndIf
QB64
Dim n As Integer
n = 1024
While n > 0
Print n
n = n \ 2
Wend
QBasic
Both loops are equivalent
i = 1024
WHILE i > 0
PRINT i
i = INT(i / 2)
WEND
PRINT
i = 1024
DO WHILE i > 0
PRINT i
i = i \ 2
LOOP
END
QuickBASIC
i = 1024
WHILE i > 0
PRINT i
i = i \ 2
WEND
Run BASIC
i = 1024
while i > 0
print i
i = int(i / 2)
wend
end
Sinclair ZX81 BASIC
The distinctive thing about a while
loop is that the conditional test happens before the loop body, not after—so that the code in the loop may be executed zero times.
Since we have no integer type, we floor the result of the division each time.
10 LET I=1024
20 IF I=0 THEN GOTO 60
30 PRINT I
40 LET I=INT (I/2)
50 GOTO 20
SmallBASIC
i = 1024
WHILE i > 0
PRINT i
i = i \ 2 ' Using \ for integer division instead of /
WEND
TI-83 BASIC
1024→I
While I>0
Disp I
I/2→I
End
TI-89 BASIC
Local i
1024 → i
While i > 0
Disp i
intDiv(i, 2) → i
EndWhile
Tiny BASIC
Tiny BASIC have no while
construct. Equivalent using conditional jump:
10 REM Loops/While
20 LET I = 1024
30 IF I <= 0 THEN GOTO 70
40 PRINT I
50 LET I = I / 2
60 GOTO 30
70 END
- Output:
1024 512 256 128 64 32 16 8 4 2 1
True BASIC
LET i = 1024
DO WHILE i > 0
PRINT i
LET i = INT(i / 2)
LOOP
END
VBA
Public Sub LoopsWhile()
Dim value As Integer
value = 1024
Do While value > 0
Debug.Print value
value = value / 2
Loop
End Sub
Visual Basic .NET
Dim x = 1024
Do
Console.WriteLine(x)
x = x \ 2
Loop While x > 0
Wee Basic
let number=1024
while number>0.5
print 1 number
let number=number/2
wend
end
XBasic
i% = 1024
DO WHILE i% > 0
PRINT i%
i% = i% / 2
LOOP
Yabasic
i = 1024
while i > 0
Print i
i = int(i / 2)
wend
end
bc
i = 1024
while (i > 0) {
i
i /= 2
}
Befunge
84*:*> :v
^/2,*25.:_@
blz
num = 1024
while num > 1 # blz will automatically cast num to a fraction when dividing 1/2, so this is necessary to stop an infinite loop
print(num)
num = num / 2
end
BQN
BQNcrate's while idiom is the closest equivalent of a while loop in the language.
_while_ ← {𝔽⍟𝔾∘𝔽_𝕣_𝔾∘𝔽⍟𝔾𝕩}
(⌊∘÷⟜2 •Show) _while_ (>⟜0) 1024
Bracmat
1024:?n & whl'(!n:>0 & out$!n & div$(!n.2):?n)
Brat
Converts to integers so output is a little bit shorter and neater.
i = 1024
while { i > 0 } {
p i
i = (i / 2).to_i
}
C
int i = 1024;
while(i > 0) {
printf("%d\n", i);
i /= 2;
}
In for loop fashion:
int i;
for(i = 1024;i > 0; i/=2){
printf("%d\n", i);
}
C#
int i = 1024;
while(i > 0){
System.Console.WriteLine(i);
i /= 2;
}
C++
int i = 1024;
while(i > 0){
std::cout << i << std::endl;
i /= 2;
}
Alternatively, it can be done with for
:
for(int i = 1024; i > 0; i /= 2)
std::cout << i << std::endl;
Instead of i /= 2
one can also use the bit shift operator i >>= 1
on integer variables.
Indeed, in C++,
for(init; cond; update){
statement;
}
is equivalent to
{
init;
while(cond){
statement;
update;
}
}
Caché ObjectScript
WHILELOOP
set x = 1024
while (x > 0) {
write x,!
set x = (x \ 2) ; using non-integer division will never get to 0
}
quit
- Output:
SAMPLES>DO ^WHILELOOP1024 512 256 128 64 32 16 8 4 2 1
Chapel
var val = 1024;
while val > 0 {
writeln(val);
val /= 2;
}
ChucK
1024 => int value;
while(value > 0)
{
<<<value>>>;
value / 2 => value;
}
Clojure
(def i (ref 1024))
(while (> @i 0)
(println @i)
(dosync (ref-set i (quot @i 2))))
2 ways without mutability:
(loop [i 1024]
(when (pos? i)
(println i)
(recur (quot i 2))))
(doseq [i (take-while pos? (iterate #(quot % 2) 1024))]
(println i))
CLU
start_up = proc ()
po: stream := stream$primary_output()
n: int := 1024
while n>0 do
stream$putl(po, int$unparse(n))
n := n/2
end
end start_up
COBOL
COBOL does not have a while loop construct, but it is does have a PERFORM UNTIL
structure, which means that the normal condition used in a while loop must be negated.
IDENTIFICATION DIVISION.
PROGRAM-ID. Loop-While.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 I PIC 9999 VALUE 1024.
PROCEDURE DIVISION.
PERFORM UNTIL NOT 0 < I
DISPLAY I
DIVIDE 2 INTO I
END-PERFORM
GOBACK
.
ColdFusion
Remove the leading space from the line break tag.
With tags:
<cfset i = 1024 /><cfloop condition="i GT 0"> #i#< br />
<cfset i /= 2 />
</cfloop>
With script:
<cfscript> i = 1024;
while( i > 0 )
{
writeOutput( i + "< br/ >" );
}
</cfscript>
Common Lisp
(let ((i 1024))
(loop while (plusp i) do
(print i)
(setf i (floor i 2))))
(loop with i = 1024
while (plusp i) do
(print i)
(setf i (floor i 2)))
(defparameter *i* 1024)
(loop while (plusp *i*) do
(print *i*)
(setf *i* (floor *i* 2)))
Cowgol
include "cowgol.coh";
var n: uint16 := 1024;
while n > 0 loop
print_i16(n);
print_nl();
n := n/2;
end loop;
Crack
i = 1024;
while( i > 0 ) {
cout ` $i\n`;
i = i/2;
}
Crystal
i = 1024
while i > 0
puts i
i //= 2
end
until condition
is the negated version, equivalent to while !(condition)
.
i = 1024
until i <= 0
puts i
i //= 2
end
D
import std.stdio;
void main() {
int i = 1024;
while (i > 0) {
writeln(i);
i >>= 1;
}
}
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Dao
i = 1024;
while( i > 0 ) i = i / 2;
Dart
void main() {
var val = 1024;
while (val > 0) {
print(val);
val >>= 2;
}
}
Instead of the bitshift operator i >>= 2, you can also use i /= 2 on double variables.
void main() {
num val = 1024;
while (val > 0) {
print(val);
val /= 2;
}
}
Dc
[ q ] sQ [ d 0!<Q p 2 / lW x ] sW 1024 lW x
DCL
DCL is quite primitive in terms of "control statements", no WHILE, REPEAT, UNLESS or FOR, so must make do with IF/THEN/ELSE and GOTO statements.
$ i = 1024
$Loop:
$ IF ( i .LE. 0 ) THEN GOTO LoopEnd
$ WRITE sys$output F$FAO( " i = !4UL", i ) ! formatted ASCII output, fixed-width field
$ ! Output alternatives:
$ ! WRITE sys$output F$STRING( i ) ! explicit integer-to-string conversion
$ ! WRITE sys$output i ! implicit conversion to string/output
$ i = i / 2
$ GOTO Loop
$LoopEnd:
Delphi
var
i : Integer;
begin
i := 1024;
while i > 0 do
begin
Writeln(i);
i := i div 2;
end;
end;
Draco
proc nonrec main() void:
word i;
i := 1024;
while i > 0 do
writeln(i);
i := i >> 1
od
corp
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Dragon
i = 1024
while(i > 0){
showln i
i >>= 1 //also acceptable: i /= 2
}
DuckDB
SQL's `WHERE` in a recursive CTE (Common Table Expression) typically acts like a "while", as noted in the first comment below.
To include 0 as the last number to be printed, comment out the last `WHERE` clause as per the "comment me out" comment.
# Start at `start`
create or replace function task(start) as table (
with recursive cte as (
select start::BIGINT as n
union all
select
n // 2 as n
from cte
where n > 0 -- "while n > 0"
)
from cte
where n > 0 -- comment me out to include the last 0
);
from task(1024);
DUP
1024[$][$.10,2/\%]# {Short form}
Explanation:
1024 {push 1024 on stack}
[ ][ ]# {while[condition>0][do]}
$ {DUP}
$. {DUP, print top of stack to STDOUT}
10, {print newline}
2/\% {2 DIV/MOD SWAP POP}
Alternative, if the interpreter allows using the shift operator:
1024[$][$.10,1»]#
Output:
1024
512
256
128
64
32
16
8
4
2
1
DWScript
var i := 1024;
while i > 0 do begin
PrintLn(i);
i := i div 2;
end;
Dyalect
var i = 1024
while i > 0 {
print(i)
i /= 2
}
E
var i := 1024
while (i > 0) {
println(i)
i //= 2
}
EasyLang
i = 1024
while i > 0
print i
i = i div 2
.
EchoLisp
(set! n 1024)
(while (> n 0) (write n) (set! n (quotient n 2)))
1024 512 256 128 64 32 16 8 4 2 1
EGL
x int = 1024;
while ( x > 0 )
SysLib.writeStdout( x );
x = MathLib.floor( x / 2 );
end
Elena
ELENA 6.x:
public program()
{
int i := 1024;
while (i > 0)
{
console.writeLine(i);
i /= 2
}
}
Elixir
defmodule Loops do
def while(0), do: :ok
def while(n) do
IO.puts n
while( div(n,2) )
end
end
Loops.while(1024)
Emacs Lisp
(let ((i 1024))
(while (> i 0)
(message "%d" i)
(setq i (/ i 2))))
EMal
int i = 1024
while i > 0
writeLine(i)
i /= 2
end
Erlang
-module(while).
-export([loop/0]).
loop() ->
loop(1024).
loop(N) when N div 2 =:= 0 ->
io:format("~w~n", [N]);
loop(N) when N >0 ->
io:format("~w~n", [N]),
loop(N div 2).
ERRE
I%=1024
WHILE I%>0 DO ! you can leave out >0
PRINT(I%)
I%=I% DIV 2 ! I%=INT(I%/2) for C-64 version
END WHILE
Euphoria
integer i
i = 1024
while i > 0 do
printf(1, "%g\n", {i})
i = floor(i/2) --Euphoria does NOT use integer division. 1/2 = 0.5
end while
Even without the floor()
the code will in fact end. But it's FAR beyond 1.
F#
let rec loop n = if n > 0 then printf "%d " n; loop (n / 2)
loop 1024
Factor
1024 [ dup 0 > ] [ dup . 2 /i ] while drop
FALSE
1024[$0>][$."
"2/]#%
Fantom
class Main
{
public static Void main ()
{
Int i := 1024
while (i > 0)
{
echo (i)
i /= 2
}
}
}
Fennel
(var n 1024)
(while (> i 0)
(print i)
(set i (// n 2)))
Fermat
Note that the test is against something between 1/2 and 1, rather than 0. Otherwise Fermat will continue printing numbers of the form 1/2^n indefinitely.
n:=1024;
while n>2/3 do !!n;n:=n/2; od;
Forth
: halving ( n -- )
begin dup 0 >
while cr dup . 2/
repeat drop ;
1024 halving
Fortran
INTEGER :: i = 1024
DO WHILE (i > 0)
WRITE(*,*) i
i = i / 2
END DO
PROGRAM LOOPWHILE
INTEGER I
C FORTRAN 77 does not have a while loop, so we use GOTO statements
C with conditions instead. This is one of two easy ways to do it.
I = 1024
10 CONTINUE
C Check condition.
IF (I .GT. 0) THEN
C Handle I.
WRITE (*,*) I
I = I / 2
C Jump back to before the IF block.
GOTO 10
ENDIF
STOP
END
PROGRAM LOOPWHILE
INTEGER I
C FORTRAN 66 does not have IF block.
I = 1024
10 CONTINUE
IF (I .LE. 0) GOTO 20
WRITE (*,*) I
I = I / 2
GOTO 10
20 CONTINUE
STOP
END
Fortress
component loops_while
export Executable
var i:ZZ32 = 1024
run() = while i > 0 do
println(i)
i := i DIV 2
end
end
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Frink
i=1024
while i>0
{
i = i/1
}
FutureBasic
window 1
long i = 1024
while i > 0
print i
i = int( i / 2 )
wend
HandleEvents
Output:
1024 512 256 128 64 32 16 8 4 2 1
GAP
n := 1024;
while n > 0 do
Print(n, "\n");
n := QuoInt(n, 2);
od;
GML
i = 1024
while(i > 0)
{
show_message(string(i))
i /= 2
}
Go
i := 1024
for i > 0 {
fmt.Printf("%d\n", i)
i /= 2
}
Groovy
Solution:
int i = 1024
while (i > 0) {
println i
i /= 2
}
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Haskell
import Control.Monad (when)
main = loop 1024
where loop n = when (n > 0)
(do print n
loop (n `div` 2))
You can use whileM_ function from monad-loops package that operates on monads:
import Data.IORef
import Control.Monad.Loops
main :: IO ()
main = do r <- newIORef 1024
whileM_ (do n <- readIORef r
return (n > 0))
(do n <- readIORef r
print n
modifyIORef r (`div` 2))
With MonadComprehensions extension you can write it a little bit more readable:
{-# LANGUAGE MonadComprehensions #-}
import Data.IORef
import Control.Monad.Loops
main :: IO ()
main = do
r <- newIORef 1024
whileM_ [n > 0 | n <- readIORef r] $ do
n <- readIORef r
print n
modifyIORef r (`div` 2)
Haxe
Using shift right.
var i = 1024;
while (i > 0) {
Sys.println(i);
i >>= 1;
}
Using integer division.
var i = 1024;
while (i > 0) {
Sys.println(i);
i = Std.int(i / 2);
}
- Output:
1024 512 256 128 64 32 16 8 4 2 1
hexiscript
let i 1024
while i > 0
println i
let i (i / 2)
endwhile
HolyC
U16 i = 1024;
while (i > 0) {
Print("%d\n", i);
i /= 2;
}
Icon and Unicon
Inform 7
let N be 1024;
while N > 0:
say "[N][line break]";
let N be N / 2;
Insitux
Use /
for floating-point division, and use (> i 0)
for full printing of the sequence (as the output of 1
here is due to the return of the last while
statement).
(var i 1024)
(while (> i 1)
(print i)
(var i (// i 2)))
- Output:
1024 512 256 128 64 32 16 8 4 2 1
J
J is array-oriented, so there is very little need for loops. For example, one could satisfy this task this way:
,. <.@-:^:*^:a: 1024
J does support loops for those times they can't be avoided (just like many languages support gotos for those time they can't be avoided).
monad define 1024
while. 0 < y do.
smoutput y
y =. <. -: y
end.
i.0 0
)
Note: this defines an anonymous function (monad define, and the subsequent lines) and passes it the argument 1024, which means it will be executed as soon as the full definition is available.
Java
int i = 1024;
while(i > 0){
System.out.println(i);
i >>= 1; //also acceptable: i /= 2;
}
With a for loop:
for(int i = 1024; i > 0;i /= 2 /*or i>>= 1*/){
System.out.println(i);
}
JavaScript
var n = 1024;
while (n > 0) {
print(n);
n /= 2;
}
In a functional idiom of JavaScript, however, we can not use a While statement to achieve this task, as statements return no value, mutate state, and can not be composed within other functional expressions.
Instead, we can define a composable loopWhile() function which has no side effects, and takes 3 arguments:
- An initial value
- A function which returns some derived value, corresponding to the body of the While loop
- A conditional function, corresponding to the While test
function loopWhile(varValue, fnDelta, fnTest) {
'use strict';
var d = fnDelta(varValue);
return fnTest(d) ? [d].concat(
loopWhile(d, fnDelta, fnTest)
) : [];
}
console.log(
loopWhile(
1024,
function (x) {
return Math.floor(x/2);
},
function (x) {
return x > 0;
}
).join('\n')
);
If we assume integer division here (Math.floor(x/2)) rather than the floating point division (x/2) used in the imperative example, we obtain the output:
512
256
128
64
32
16
8
4
2
1
Joy
DEFINE putln == put '\n putch.
1024 [] [dup putln 2 /] while.
jq
Using recurse/1
# To avoid printing 0, test if the input is greater than 1
1024 | recurse( if . > 1 then ./2 | floor else empty end)
Using recurse/2 (requires jq >1.4)
1024 | recurse( ./2 | floor; . > 0)
Using a filter
def task: if . > 0 then ., (./2 | floor | task) else empty end;
1024|task
Using while/2
If your jq does not include while/2 as a builtin, here is its definition:
def while(cond; update):
def _while: if cond then ., (update | _while) else empty end;
_while;
For example:
1024|while(. > 0; ./2|floor)
Jsish
#!/usr/bin/env jsish
/* Loops/While in Jsish */
var i = 1024;
while (i > 0) { puts(i); i = i / 2 | 0; }
/*
=!EXPECTSTART!=
1024
512
256
128
64
32
16
8
4
2
1
=!EXPECTEND!=
*/
- Output:
prompt$ jsish -u loopsWhile.jsi [PASS] loopsWhile.jsi
Julia
n = 1024
while n > 0
println(n)
n >>= 1
end
- Output:
1024 512 256 128 64 32 16 8 4 2 1
K
Implementation of the task using anonymous function is given below
{while[x>0; \echo x; x%:2]} 1024
Kotlin
// version 1.0.6
fun main(args: Array<String>) {
var value = 1024
while (value > 0) {
println(value)
value /= 2
}
}
- Output:
1024 512 256 128 64 32 16 8 4 2 1
LabVIEW
Use Round Towards -Inf to prevent the integer becoming a float.
This image is a VI Snippet, an executable image of LabVIEW code. The LabVIEW version is shown on the top-right hand corner. You can download it, then drag-and-drop it onto the LabVIEW block diagram from a file browser, and it will appear as runnable, editable code.
Lambdatalk
{def loops_while
{lambda {:i}
{if {< :i 1}
then (end of loop)
else :i {loops_while {/ :i 2}}}}}
-> loops_while
{loops_while 1024}
-> 1024 512 256 128 64 32 16 8 4 2 1 (end of loop)
Alternative solution:
{def while
{lambda {:i}
{if {< :i 1}
then
else {br}:i {while {/ :i 2}}}}}
{while 1024} ->
1024
512
256
128
64
32
16
8
4
2
1
Lang
$n = 1024
while($n > 0) {
fn.println($n)
$n //= 2
}
Lang5
: /i / int ; : 0= 0 == ;
: dip swap '_ set execute _ ; : dupd 'dup dip ;
: 2dip swap '_x set swap '_y set execute _y _x ;
: while
do dupd 'execute 2dip
rot 0= if break else dup 2dip then
loop ;
1024 "dup 0 >" "dup . 2 /i" while
langur
var i = 1024
while i > 0 {
writeln i
i \= 2
}
Lasso
local(i = 1024)
while(#i > 0) => {^
#i + '\r'
#i /= 2
^}
LDPL
data:
n is number
procedure:
store 1024 in n
while n is greater than 0 do
display n lf
divide n by 2 in n
floor n
repeat
LIL
set num 1024; while {$num > 0} {print $num; set num [expr $num \ 2]}
Backslash is integer division, otherwise LIL would allow the division to go floating point.
Lingo
n = 1024
repeat while n>0
put n
n = n/2 -- integer division implicitely returns floor: 1/2 -> 0
end repeat
Lisaac
+ i : INTEGER;
i := 1024;
{ i > 0 }.while_do {
i.println;
i := i / 2;
};
LiveCode
put 1024 into n
repeat while n > 0
put n & cr
divide n by 2
end repeat
Logo
make "n 1024
while [:n > 0] [print :n make "n :n / 2]
LOLCODE
LOLCODE's loop semantics require an afterthought if a condition is used, thus the nop in the following example. The more idiomatic approach would have been to GTFO of the loop once n had reached 0.
HAI 1.3
I HAS A n ITZ 1024
IM IN YR loop UPPIN YR nop WILE n
VISIBLE n
n R QUOSHUNT OF n AN 2
IM OUTTA YR loop
KTHXBYE
Lua
n = 1024
while n>0 do
print(n)
n = math.floor(n/2)
end
M2000 Interpreter
Module Checkit {
Def long A=1024
While A>0 {
Print A
A/=2
}
}
Checkit
One line
Module Online { A=1024&: While A>0 {Print A: A/=2}} : OnLine
m4
This ‘loop’ is really a tail recursion, which m4 implementations generally do not optimize.
divert(-1)
define(`loop',
`ifelse(eval(0 < ($1)),1,`$1`
'loop(eval(($1) / 2))')')
divert`'dnl
loop(1024)dnl
- Output:
$ m4 loops_while.m4
1024 512 256 128 64 32 16 8 4 2 1
Make
NEXT=`expr $* / 2`
MAX=10
all: $(MAX)-n;
0-n:;
%-n: %-echo
@-make -f while.mk $(NEXT)-n MAX=$(MAX)
%-echo:
@echo $*
Invoking it
|make -f while.mk MAX=1024
Maple
To avoid generating an infinite sequence (1/2, 1/4, 1/8, 1/16, etc.) of fractions after n takes the value 1, we use integer division (iquo) rather than the solidus operation (/).
> n := 1024: while n > 0 do print(n); n := iquo(n,2) end:
1024
512
256
128
64
32
16
8
4
2
1
Mathematica /Wolfram Language
Mathematica does not support integer-rounding, it would result in getting fractions: 1/2, 1/4 , 1/8 and so on; the loop would take infinite time without using the Floor function:
i = 1024;
While[i > 0,
Print[i];
i = Floor[i/2];
]
MATLAB / Octave
In Matlab (like Octave) the math is done floating point, then rounding to integer, so that 1/2 will be always 1 and never 0. A 'floor' is used to round the number.
i = 1024;
while (i > 0)
disp(i);
i = floor(i/2);
end
A vectorized version of the code is
printf('%d\n', 2.^[log2(1024):-1:0]);
Maxima
block([n], n: 1024, while n > 0 do (print(n), n: quotient(n, 2)));
/* using a C-like loop: divide control variable by two instead of incrementing it */
for n: 1024 next quotient(n, 2) while n > 0 do print(n);
MAXScript
a = 1024
while a > 0 do
(
print a
a /= 2
)
Metafont
Metafont has no while loop, but it can be "simulated" easily.
a := 1024;
forever: exitif not (a > 0);
show a;
a := a div 2;
endfor
Mia
i = 1024
while i > 0 {
print i
i = i :/ 2
}
min
1024 :n (n 0 >) (n puts 2 div @n) while
MiniScript
i = 1024
while i > 0
print i
i = floor(i/2)
end while
- Output:
1024 512 256 128 64 32 16 8 4 2 1
MIRC Scripting Language
alias while_loop {
var %n = 10
while (%n >= 0) {
echo -a Countdown: %n
dec %n
}
}
MIXAL
******************************************
* X = M / N WHILE X > 0
* STORE EACH X IN NUMERIC ARRAY
* PRINT ARRAY
*******************************************
M EQU 1024
N EQU 2
LPR EQU 18
BUF0 EQU 100
MSG EQU 2000
LENGTH EQU 500
ORIG 3000
START IOC 0(LPR)
ENTX M
CALC STX BUF0,1
DIV =N=
SRAX 5
INC1 1
JXP CALC
ST1 LENGTH
PRINT LDA BUF0,2
CHAR
STX MSG
OUT MSG(LPR)
INC2 1
CMP2 LENGTH
JNE PRINT
HLT
END START
МК-61/52
1 0 2 4 П0 ИП0 /-/ x<0 15 ИП0
2 / П0 БП 05 С/П
Modula-2
MODULE DivBy2;
IMPORT InOut;
VAR
i: INTEGER;
BEGIN
i := 1024;
WHILE i > 0 DO
InOut.WriteInt(i, 4);
InOut.WriteLn;
i := i DIV 2
END
END DivBy2.
Modula-3
The usual module code and imports are omitted.
PROCEDURE DivBy2() =
VAR i: INTEGER := 1024;
BEGIN
WHILE i > 0 DO
IO.PutInt(i);
IO.Put("\n");
i := i DIV 2;
END;
END DivBy2;
Monte
var i := 1024
while (i > 0):
traceln(i)
i //= 2
MOO
i = 1024;
while (i > 0)
player:tell(i);
i /= 2;
endwhile
Morfa
import morfa.io.print;
var i = 1024;
while(i > 0)
{
println(i);
i /= 2;
}
Nanoquery
$n = 1024
while ($n > 0)
println $n
$n = $n/2
end while
Neko
var i = 1024
while(i > 0) {
$print(i + "\n");
i = $idiv(i, 2)
}
Nemerle
mutable x = 1024;
while (x > 0)
{
WriteLine($"$x");
x /= 2;
}
Or, with immutable types, after Haskell:
// within another function, eg Main()
def loop(n : int) : void
{
when (n > 0)
{
WriteLine($"$n");
loop(n / 2);
}
}
loop(1024)
NetRexx
/* NetRexx */
options replace format comments java crossref savelog symbols nobinary
say
say 'Loops/While'
x_ = 1024
loop while x_ > 0
say x_.right(6)
x_ = x_ % 2 -- integer division
end
NewLISP
(let (i 1024)
(while (> i 0)
(println i)
(setq i (/ i 2))))
Nim
var n: int = 1024
while n > 0:
echo(n)
n = n div 2
Oberon-2
The usual module code and imports are ommited.
PROCEDURE DivBy2*();
VAR i: INTEGER;
BEGIN
i := 1024;
WHILE i > 0 DO
Out.Int(i,0);
Out.Ln;
i := i DIV 2;
END;
END DivBy2;
Objeck
i := 1024;
while(i > 0) {
i->PrintLine();
i /= 2;
};
ObjectIcon
An important thing here is the test for termination is a succeed-or-fail operation, rather than a boolean expression. No boolean value is written to the output; rather, the whole statement fails when n reaches zero. The expression 0 < n either returns n or fails.
import io
procedure main()
local n
n := 1024
while n := write(0 < n) / 2
end
- Output:
$ oit -s loops_while-oi.icn && ./loops_while-oi
1024 512 256 128 64 32 16 8 4 2 1
The following also works, and shows a way to avoid having to code the method of writing the output into the loop itself.
import io
procedure main()
local coexpression
coexpression := create generator(1024)
while write(@coexpression)
end
procedure generator(n)
while 0 < n do { suspend n; n /:= 2 }
end
To show what I mean, let’s do some (merely illustrative) loop-unrolling where the output gets written.
import io
procedure main()
local coexpression
coexpression := create generator(1024)
write(@coexpression) &
write(@coexpression) &
write(@coexpression) &
write(@coexpression)&
while (write(@coexpression) &
write(@coexpression) &
write(@coexpression) &
write(@coexpression))
end
procedure generator(n)
while 0 < n do { suspend n; n /:= 2 }
end
OCaml
let n = ref 1024;;
while !n > 0 do
Printf.printf "%d\n" !n;
n := !n / 2
done;;
But it is more common to write it in a tail-recursive functional style:
let rec loop n =
if n > 0 then begin
Printf.printf "%d\n" n;
loop (n / 2)
end
in loop 1024
Octave
i = 1024;
while (i > 0)
disp(i)
i = floor(i/2);
endwhile
The usage of the type int32 is not convenient, since the math is done floating point, then rounding to integer, so that 1/2 will be always 1 and never 0.
Odin
Odin only has one loop type: for
package main
import "core:fmt"
main :: proc() {
for i := 1024 ; i > 0 ; i /= 2 {
fmt.println(i)
}
}
Oforth
1024 while ( dup ) [ dup println 2 / ]
OOC
main: func {
value := 1024
while (value > 0) {
value toString() println()
value /= 2
}
}
Oz
Oz' for-loop can be used in a C-like manner:
for I in 1024; I>0; I div 2 do
{Show I}
end
Alternatively, we can use the while
feature of the for-loop with a mutable variable:
declare
I = {NewCell 1024}
in
for while:@I > 0 do
{Show @I}
I := @I div 2
end
Panda
Panda doesn't have explicit loops, instead we solve it by using the transitive closure operator. It applies a function to each successive value, each unique value is outputted. Our function halves, we make sure that the result is greater than 0 and add newline.
fun half(a) type integer->integer a.divide(2)
1024.trans(func:half).gt(0) nl
Panoramic
dim x%:rem an integer
x%=1024
while x%>0
print x%
x%=x%/2
end_while
rem output starts with 1024 and ends with 1.
terminate
PARI/GP
n=1024;
while(n,
print(n);
n/=2
);
Pascal
program divby2(output);
var
i: integer;
begin
i := 1024;
while i > 0 do
begin
writeln(i);
i := i div 2
end
end.
PascalABC.NET
##
var n := 1024;
while n > 0 do
begin
Println(n);
n := n div 2;
end;
PeopleCode
Local string &CRLF;
Local number &LoopNumber;
&LoopNumber = 1024;
&CRLF = Char(10) | Char(13);
While &LoopNumber > 0;
WinMessage(&LoopNumber | &CRLF);
&LoopNumber = &LoopNumber / 2;
End-While;
Perl
my $n = 1024;
while($n){
print "$n\n";
$n = int $n / 2;
}
or written as a for-loop and using the bit-shift operator
for(my $n = 1024; $n > 0; $n >>= 1){
print "$n\n";
}
until (condition)
is equivalent to while (not condition)
.
my $n = 1024;
until($n == 0){
print "$n\n";
$n = int $n / 2;
}
Phix
integer i = 1024 while i!=0 do ?i i = floor(i/2) -- (see note) end while
note: using i=i/2 would iterate over 1000 times until i is 4.94e-324 before the final division made it 0, if it didn't typecheck when it got set to 0.5
Phixmonti
/# Rosetta Code problem: https://rosettacode.org/wiki/Loops/While
by Galileo, 11/2022 #/
include ..\Utilitys.pmt
1024 dup while dup ? 2 / int dup endwhile
- Output:
1024 512 256 128 64 32 16 8 4 2 1 === Press any key to exit ===
PHL
var i = 1024;
while (i > 0) {
printf("%i\n", i);
i = i/2;
}
PHP
$i = 1024;
while ($i > 0) {
echo "$i\n";
$i >>= 1;
}
Picat
While loop
go =>
N = 1024,
while (N > 0)
println(N),
N := N // 2
end.
Recursion
go2 =>
while_loop(1024).
while_loop(0) => true.
while_loop(N) =>
println(N),
while_loop(N//2).
PicoLisp
(let N 1024
(while (gt0 N)
(println N)
(setq N (/ N 2)) ) )
Pike
int main(){
int i = 1024;
while(i > 0){
write(i + "\n");
i = i / 2;
}
}
PL/0
var i;
begin
i := 1024;
while i > 0 do
begin
! i;
i := i / 2
end;
end.
- Output:
1024 512 256 128 64 32 16 8 4 2 1
PL/I
declare i fixed binary initial (1024);
do while (i>0);
put skip list (i);
i = i / 2;
end;
PL/SQL
set serveroutput on
declare
n number := 1024;
begin
while n > 0 loop
dbms_output.put_line(n);
n := trunc(n / 2);
end loop;
end;
/
Plain English
To run:
Start up.
Show the halvings of 1024.
Wait for the escape key.
Shut down.
To show the halvings of a number:
If the number is 0, exit.
Convert the number to a string.
Write the string to the console.
Divide the number by 2.
Repeat.
Pop11
lvars i = 1024;
while i > 0 do
printf(i, '%p\n');
i div 2 -> i;
endwhile;
PostScript
PostScript has no real while
loop,
but it can easily be created with an endless loop and a check at the beginning:
1024
{
dup 0 le % check whether still greater than 0
{ pop exit } % if not, exit the loop
if
dup = % print the number
2 idiv % divide by two
}
loop
PowerShell
[int]$i = 1024
while ($i -gt 0) {
$i
$i /= 2
}
Prolog
while(0) :- !.
while(X) :-
writeln(X),
X1 is X // 2,
while(X1).
Start the calculation at a top-level like this:
?- while(1024).
Python
n = 1024
while n > 0:
print n
n //= 2
Quackery
1024
[ dup 0 > while
dup echo cr 2 /
again ]
drop
- Output:
1024 512 256 128 64 32 16 8 4 2 1
R
i <- 1024L
while(i > 0)
{
print(i)
i <- i %/% 2
}
Racket
Loop/When
#lang racket
(let loop ([n 1024])
(when (positive? n)
(displayln n)
(loop (quotient n 2))))
Macro
#lang racket
(define-syntax-rule (while condition body ...)
(let loop ()
(when condition
body ...
(loop))))
(define n 1024)
(while (positive? n)
(displayln n)
(set! n (sub1 n)))
Raku
(formerly Perl 6)
Here is a straightforward translation of the task description:
my $n = 1024; while $n > 0 { say $n; $n div= 2 }
The same thing with a C-style loop and a bitwise shift operator:
loop (my $n = 1024; $n > 0; $n +>= 1) { say $n }
And here's how you'd really write it, using a sequence operator that intuits the division for you:
.say for 1024, 512, 256 ... 1
REBOL
REBOL [
Title: "Loop/While"
URL: http://rosettacode.org/wiki/Loop/While
]
value: 1024
while [value > 0][
print value
value: to-integer value / 2
]
ReScript
let n = ref(1024)
while n.contents > 0 {
Js.log(n.contents)
n := n.contents / 2
}
Retro
1024 [ cr &putn sip 2 / dup ] while
REXX
version 1, simple
/*REXX program demonstrates a DO WHILE with index reduction construct.*/
j=1024 /*define the initial value of J.*/
do while j>0 /*test if made at the top of DO.*/
say j
j=j%2 /*in REXX, % is integer division.*/
end
/*stick a fork in it, we're done.*/
- Output:
1024 512 256 128 64 32 16 8 4 2 1
version 2, right justified
Note that a faster version could be implemented with
- DO WHILE x\==0
but that wouldn't be compliant with the wording of the task.
/*REXX program demonstrates a DO WHILE with index reduction construct.*/
x=1024 /*define the initial value of X.*/
do while x>0 /*test if made at the top of DO.*/
say right(x,10) /*pretty output by aligning right*/
x=x%2 /*in REXX, % is integer division.*/
end
/*stick a fork in it, we're done.*/
- Output:
1024 512 256 128 64 32 16 8 4 2 1
version 3, faster WHILE comparison
/*REXX program demonstrates a DO WHILE with index reduction construct.*/
x=1024 /*define the initial value of X.*/
do while x>>0 /*this is an exact comparison. */
say right(x,10) /*pretty output by aligning right*/
x=x%2 /*in REXX, % is integer division.*/
end
/*stick a fork in it, we're done.*/
output is the same as version 2.
version 4, index reduction
/*REXX program demonstrates a DO WHILE with index reduction construct.*/
/* [↓] note: BY defaults to 1*/
do j=1024 by 0 while j>>0 /*this is an exact comparison. */
say right(j,10) /*pretty output by aligning right*/
j=j%2 /*in REXX, % is integer division.*/
end
/*stick a fork in it, we're done.*/
output is the same as version 2.
Ring
i = 1024
while i > 0
see i + nl
i = floor(i / 2)
end
Rockstar
The sky is a television on fire.
The floor is ornamental.
The table is hydrochloric.
While the sky is higher than the floor,
Shout the sky.
Put the sky over the table into the sky.
(Rockstar is known for doing that JavaScript quirk, since all numbers are floats, but due to it having the same limits as JavaScript and the most popular interpreter being JS-based, the loop is finite, yet you don't get the result you would get in something like Python.)
RPL
≪ 1024 WHILE DUP REPEAT DUP 1 DISP 2 / END DROP ≫
Ruby
i = 1024
while i > 0 do
puts i
i /= 2
end
The above can be written in one statement:
puts i = 1024
puts i /= 2 while i > 0
until condition
is equivalent to while not condition
.
i = 1024
until i <= 0 do
puts i
i /= 2
end
Rust
fn main() {
let mut n: i32 = 1024;
while n > 0 {
println!("{}", n);
n /= 2;
}
}
SAS
data _null_;
n=1024;
do while(n>0);
put n;
n=int(n/2);
end;
run;
Sather
class MAIN is
main is
i ::= 1024;
loop while!(i > 0);
#OUT + i + "\n";
i := i / 2;
end;
end;
end;
Scala
Imperative
var i = 1024
while (i > 0) {
println(i)
i /= 2
}
Tail recursive
@tailrec
def loop(iter: Int) {
if (iter > 0) {
println(iter)
loop(iter / 2)
}
}
loop(1024)
Iterator
def loop = new Iterator[Int] {
var i = 1024
def hasNext = i > 0
def next(): Int = { val tmp = i; i = i / 2; tmp }
}
loop.foreach(println(_))
Stream
Finite stream (1024..0) filtered by takeWhile (1024..1).
def loop(i: Int): Stream[Int] = i #:: (if (i > 0) loop(i / 2) else Stream.empty)
loop(1024).takeWhile(_ > 0).foreach(println(_))
Scheme
(do ((n 1024 (quotient n 2)))
((<= n 0))
(display n)
(newline))
Scilab
i=1024
while i>0
printf("%4d\n",i)
i=int(i/2)
end
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Seed7
$ include "seed7_05.s7i";
const proc: main is func
local
var integer: i is 1024;
begin
while i > 0 do
writeln(i);
i := i div 2
end while;
end func;
- Output:
1024 512 256 128 64 32 16 8 4 2 1
SenseTalk
put 1024 into x
log x
Repeat until x = 1
divide x by 2
log x
End repeat
SETL
n := 1024;
while n > 0 loop
print( n );
n := n div 2;
end loop;
Sidef
var i = 1024
while (i > 0) {
say i
i //= 2
}
Simula
begin
integer i;
i:=1024;
while i>0 do
begin
outint(i,5);
i:=i//2-1
end
end
- Output:
1024 511 254 126 62 30 14 6 2
Slate
#n := 1024.
[n isPositive] whileTrue:
[inform: number printString.
n := n // 2]
Smalltalk
The Block (aka lambda closure) class provides a number of loop messages; with test at begin, test at end and with exit (break).
[s atEnd] whileFalse: [s next. ...].
[foo notNil] whileTrue: [s next. ...].
[...] doWhile: [ ... someBooleanExpression ].
[...] doUntil: [ ... someBooleanExpression ].
[:exit | ... cold ifTrue:[exit value]. ...] loopWithExit
Examples:
number := 1024.
[ number > 0 ] whileTrue:
[ Transcript print: number; nl.
number := number // 2 ]
number := 1024.
[ number <= 0 ] whileFalse:
[ Transcript print: number; nl.
number := number // 2 ]
Sparkling
var i = 1024;
while i > 0 {
print(i);
i /= 2;
}
Spin
con
_clkmode = xtal1 + pll16x
_clkfreq = 80_000_000
obj
ser : "FullDuplexSerial.spin"
pub main | n
ser.start(31, 30, 0, 115200)
n := 1024
repeat while n > 0
ser.dec(n)
ser.tx(32)
n /= 2
waitcnt(_clkfreq + cnt)
ser.stop
cogstop(0)
- Output:
1024 512 256 128 64 32 16 8 4 2 1
SPL
n = 1024
>
#.output(n)
n /= 2
< n!<1
- Output:
1024 512 256 128 64 32 16 8 4 2 1
SQL PL
version 9.7 or higher.
With SQL PL:
--#SET TERMINATOR @
SET SERVEROUTPUT ON @
BEGIN
DECLARE I SMALLINT DEFAULT 1024;
Loop: WHILE (I > 0) DO
CALL DBMS_OUTPUT.PUT_LINE(I);
SET I = I / 2;
END WHILE Loop;
END @
Output:
db2 -td@ db2 => SET SERVEROUTPUT ON @ DB20000I The SET SERVEROUTPUT command completed successfully. db2 => BEGIN ... db2 (cont.) => END @ DB20000I The SQL command completed successfully. 1024 512 256 128 64 32 16 8 4 2 1
Standard ML
val n = ref 1024;
while !n > 0 do (
print (Int.toString (!n) ^ "\n");
n := !n div 2
)
But it is more common to write it in a tail-recursive functional style:
let
fun loop n =
if n > 0 then (
print (Int.toString n ^ "\n");
loop (n div 2)
) else ()
in
loop 1024
end
Stata
local n=1024
while `n'>0 {
display `n'
local n=floor(`n'/2)
}
Suneido
i = 1024
while (i > 0)
{
Print(i)
i = (i / 2).Floor()
}
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Swift
var i = 1024
while i > 0 {
println(i)
i /= 2
}
Tailspin
In Tailspin you can loop by sending a value back to the matchers (by "-> #"). Depending on how you set that up, you create different loops.
1024 -> \(
<0~..> '$;$#10;' -> !OUT::write
$ ~/ 2 -> #
\) -> !VOID
TAV
i =: 1024
?* i >= 1
print i
i =: i // 2 \ integer division"
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Tcl
set i 1024
while {$i > 0} {
puts $i
set i [expr {$i / 2}]
}
Plain TeX
\newcount\rosetta
\rosetta=1024
\loop
\the\rosetta\endgraf
\divide\rosetta by 2
\ifnum\rosetta > 0
\repeat
\end
TorqueScript
This has to make use of mFloor because torque has automatic type shuffling, causing an infiniteloop.
%num = 1024;
while(%num > 0)
{
echo(%num);
%num = mFloor(%num / 2);
}
Transact-SQL
DECLARE @i INT = 1024;
WHILE @i >0
BEGIN
PRINT @i;
SET @i = @i / 2;
END;
Trith
1024 [dup print 2 / floor] [dup 0 >] while drop
1024 [dup print 1 shr] [dup 0 >] while drop
TUSCRIPT
$$ MODE TUSCRIPT
i=1024
LOOP
PRINT i
i=i/2
IF (i==0) EXIT
ENDLOOP
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Unicon
See Icon.
Uniface
variables
numeric I
endvariables
I = 1024
while (I > 0)
putmess I
I = (I/2)[trunc]
endwhile
UNIX Shell
x=1024
while [[ $x -gt 0 ]]; do
echo $x
x=$(( $x/2 ))
done
UnixPipes
(echo 1024>p.res;tail -f p.res) | while read a ; do
test $a -gt 0 && (expr $a / 2 >> p.res ; echo $a) || exit 0
done
Ursa
decl int n
set n 1024
while (> n 0)
out n endl console
set n (int (/ n 2))
end while
Ursala
Unbounded iteration is expressed with the -> operator. An expression (p-> f) x, where p is a predicate and f is a function, evaluates to x, f(x), or f(f(x)), etc. as far as necessary to falsify p.
Printing an intermediate result on each iteration is a bigger problem because side effects are awkward. Instead, the function g in this example iteratively constructs a list of results, which is displayed on termination.
The argument to g is the unit list <1024>. The predicate p is ~&h, the function that tests whether the head of a list is non-null (equivalent to non-zero). The iterated function f is that which conses the truncated half of the head of its argument with a copy of the whole argument. The main program takes care of list reversal and formatting.
#import nat
g = ~&h-> ^C/half@h ~&
#show+
main = %nP*=tx g <1024>
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Explicit iteration has its uses but there are always alternatives. The same output is produced by the following main program using bit manipulation.
main = %nP*=tK33 1024
V
1024 [0 >] [
dup puts
2 / >int
] while
Vala
int i = 1024;
while (i > 0) {
stdout.printf("%d\n", i);
i /= 2;
}
Vedit macro language
#1 = 1024
while (#1 > 0) {
Num_Type(#1)
#1 /= 2
}
or with for loop:
for (#1 = 1024; #1 > 0; #1 /= 2) {
Num_Type(#1)
}
Verbexx
// Basic @LOOP while: verb
@LOOP init:{@VAR n = 1024} while:(n > 0) next:{n /= 2}
{
@SAY n;
};
Verilog
module main;
integer i;
initial begin
i = 1024;
while( i > 0) begin
$display(i);
i = i / 2;
end
$finish ;
end
endmodule
Vim Script
let i = 1024
while i > 0
echo i
let i = i / 2
endwhile
V (Vlang)
fn main() {
mut i := 1024
for i > 0 {
println(i)
i /= 2
}
}
- Output:
1024 512 256 128 64 32 16 8 4 2 1
Wart
i <- 1024
while (i > 0)
prn i
i <- (int i/2)
Whitespace
Pseudo-assembly equivalent:
push 1024
0:
dup onum push 10 ochr
push 2 div dup
push 0 swap sub
jn 0
pop exit
Wren
var i = 1024
while (i > 0) {
System.print(i)
i = (i / 2).floor
}
- Output:
1024 512 256 128 64 32 16 8 4 2 1
X86 Assembly
; NASM 64 bit X86-64 assembly on Linux
global main
extern printf
segment .data
printffmt db `%ld\n`,0
segment .text
main:
push rbp
mov rbp,rsp
; used rbx and r12 because printf preserves these values
mov rbx,1024 ; start with 1024
mov r12,2 ; load 2 as divisor
.toploop ; top of while loop
cmp rbx,0 ; compare to 0
jle .done ; exit 0 or less
lea rdi,[printffmt] ; print number in rsi
mov rsi,rbx ; mov to rsi as argument
call printf
; calculate n/2 and save
xor rdx,rdx ; clear rdx for division
mov rax,rbx ; mov number to rax for division
idiv r12 ; divide by 2
mov rbx,rax ; save n/2
jmp .toploop ; next loop
.done
xor rax,rax ; return code 0
leave ; fix stack
ret ; return
XLISP
The specification calls for an integer value and for the loop to run WHILE that value is greater than zero. In a dynamically typed language like XLISP, variables cannot be declared as integer or real; but the same result is obtained by looping WHILE the value of the variable i is greater than or equal to one.
(DEFINE I 1024)
(WHILE (>= I 1)
(PRINT I)
(DEFINE I (/ I 2)))
XPL0
code CrLf=9, IntOut=11;
int I;
[I:= 1024;
while I>0 do
[IntOut(0, I); CrLf(0);
I:= I>>1; \(same as I/2 for positive I)
];
]
Z80 Assembly
Use the /S8 switch on the ZSM4 assembler for 8 significant characters for labels and names
;
; while loop, dividing 1024 repeatedly by 2, using Z80 assembly language
;
; Runs under CP/M 3.1 on YAZE-AG-2.51.2 Z80 emulator
; Assembled with zsm4 on same emulator/OS, uses macro capabilities of said assembler
; Created with vim under Windows
;
; Thanks to https://wikiti.brandonw.net for the idea for the conversion routine hl -> decimal ASCII
;
;
; 2023-05-19 Xorph
;
;
; Useful definitions
;
bdos equ 05h ; Call to CP/M BDOS function
strdel equ 6eh ; Set string delimiter
wrtstr equ 09h ; Write string to console
nul equ 00h ; ASCII control characters
cr equ 0dh
lf equ 0ah
cnull equ '0' ; ASCII character constants
;
; Macros for BDOS calls
;
setdel macro char ; Set string delimiter to char
ld c,strdel
ld e,char
call bdos
endm
print macro msg ; Output string to console
ld c,wrtstr
ld de,msg
call bdos
endm
newline macro ; Print newline
ld c,wrtstr
ld de,crlf
call bdos
endm
;
; =====================
; Start of main program
; =====================
;
cseg
setdel nul ; Set string delimiter to 00h
ld ix,value ; Register ix points to memory location of counter
while:
ld a,(ix) ; Z80 has no 16 bit compare, so we check the value byte by byte for 0
or a ; In contrast to other CPUs, loading a register does NOT set the flags
jr nz,docalc ; or-ing the accumulator with itself sets the flags and is faster than "cp 0"
ld a,(ix+1)
or a
jr z,endprog ; If both bytes are 0, end program - this jump could be optimized away
; and replaced with a direct "ret z", but we want to simulate a "real"
; while loop, so we continue (jump to) after the last loop statement
docalc:
ld hl,(value) ; Print the current value, followed by newline
ld iy,buffer ; Register iy points to memory location for current value as text for printout
call dispHL ; dispHL modifies iy, so it must be reset to the buffer on every iteration
print buffer
newline
srl (ix+1) ; Neither has the Z80 a 16 bit shift operation for dividing by 2...
rr (ix) ; Shift the MSB of value right and then rotate the LSB with carry to the right
jr while ; Next iteration
endprog:
ret ; Return to CP/M
;
; ===================
; End of main program
; ===================
;
;
; Helper routines - notice that the Z80 does not have a divide instruction
; Notice further that CP/M does not have any support for pretty-printing
; formatted numbers and stuff like that. So we have to do all this by hand...
;
;
; Converts the value (unsigned int) in register hl to its decimal representation
; Register iy has memory address of target for converted value
; String is terminated with nul character (\0)
;
dispHL:
ld b,1 ; Flag for leading '0'
irp x,<-10000,-1000,-100,-10,-1>
ld de,x ; Subtract powers of 10 and determine digit
call calcdig
endm
ld a,nul ; Terminate result string with nul
ld (iy+0),a
ret ; End of conversion routine
calcdig:
ld a,cnull-1 ; Determine the digit character
incrdig:
inc a ; Start with '0'
add hl,de ; As long as subtraction is possible, increment digit character
jr c,incrdig
sbc hl,de ; If negative, undo last subtraction and continue with remainder
cp cnull ; Check for leading '0', these are ignored
jr nz,adddig
bit 0,b ; Use bit instruction for check if flag set, register a contains digit
ret nz ; If '0' found and flag set, it is a leading '0' and we return
adddig:
ld b,0 ; Reset flag for leading '0', we are now outputting digits
ld (iy+0),a ; Store character in memory and set iy to next location
inc iy
ret ; End of conversion helper routine
;
; ================
; Data definitions
; ================
;
dseg
value: defw 1024d ; Starting value for loop, 16 bit little endian
crlf: defb cr,lf,nul ; Generic newline
buffer: defs 10 ; Buffer for conversion of number to text
- Output:
E>whilelp 1024 512 256 128 64 32 16 8 4 2 1
Zig
const std = @import("std");
pub fn main() void {
var i: u11 = 1024;
while (i > 0) : (i /= 2)
std.debug.print("{}\n", .{i});
}
zkl
n:=1024; while(n>0){println(n); n/=2;}
- Output:
1024 512 256 128 64 32 16 8 4 2 1