Loops/While
You are encouraged to solve this task according to the task description, using any language you may know.
Start an integer value at 1024. Loop while it is greater than 0. Print the value (with a newline) and divide it by two each time through the loop.
ActionScript
<lang actionscript> var i:int = 1024; while (i > 0) {
trace(i); i /= 2;
} </lang>
Ada
<lang ada> declare
I : Integer := 1024;
begin
while I > 0 loop
Put_Line(Integer'Image(I));
I := I / 2;
end loop;
end; </lang>
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
AmigaE
<lang amigae>PROC main()
DEF i = 1024
WHILE i > 0
WriteF('\d\n', i)
i := i / 2
ENDWHILE
ENDPROC</lang>
AutoHotkey
<lang AutoHotkey> i = 1024 While (i > 0) {
output = %output%`n%i% i := Floor(i / 2)
} MsgBox % output </lang>
AWK
<lang awk>BEGIN {
v = 1024
while(v > 0) {
print v
v = int(v/2)
}
}</lang>
BASIC
<lang qbasic>i = 1024 while i > 0
print i i = i / 2
wend</lang>
Befunge
84*:*> :v
^/2.:_@
C
<lang c>int i = 1024; while(i > 0) {
printf("%d\n", i);
i /= 2;
}</lang> In for loop fashion: <lang c>int i; for(i = 1024;i > 0; i/=2){
printf("%d\n", i);
}</lang>
C++
<lang cpp>int i = 1024; while(i > 0) {
std::cout << i << std::endl; i /= 2;
}</lang>
Alternatively, it can be done with for:
<lang cpp>
for (int i = 1024; i>0; i /= 2)
std::cout << i << std::endl;
</lang> Indeed, in C++, <lang cpp> for (init; cond; update)
statement;
</lang> is equivalent to <lang cpp> {
init;
while (cond)
{
statement;
update;
}
} </lang>
C#
<lang c>int i = 1024; while(i > 0){
System.Console.WriteLine(i); i /= 2;
}</lang>
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
<lang lisp>(setq i 1024) (loop while (> i 0) do
(print i) (setq i (floor i 2)))</lang>
D
<lang d>import std.stdio;
int i = 1024; void main() {
while(i > 0) {
writefln("%s", i);
i >>= 1;
}
}</lang>
E
<lang e>var i := 1024 while (i > 0) {
println(i) i //= 2
}</lang>
FALSE
1024[$0>][$." "2/]#%
Forth
<lang forth>
: halving ( n -- ) begin dup 0 > while cr dup . 2/ repeat drop ; 1024 halving
</lang>
Factor
1024 [ dup 0 > ] [ dup . 2 /i ] [ drop ] while
Fortran
<lang fortran>
INTEGER :: i = 1024 DO WHILE (i > 0) WRITE(*,*) i i = i / 2 END DO
</lang>
Haskell
<lang haskell>
import Control.Monad
main = loop 1024
where loop n = when (n > 0)
(do print n
loop (n `div` 2))
</lang>
Icon
<lang icon>
procedure main() local i i := 1024 while write(0 < (i := i / 2)) end
</lang>
J
J is array-oriented, so there is very little need for loops. For example, one could satisfy this task this way:
<lang j>
,. <.@-:^:*^:a: 1024
</lang>
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).
<lang j>
3 : 0 ] 1024
while. 0 < y do.
y 1!:2 ] 2
y =. <. -: y
end.
i. 0 0
)
</lang>
Though it's rare to see J code like this.
Java
<lang java5>int i = 1024; while(i > 0){
System.out.println(i); i >>= 1; //also acceptable: i /= 2;
}</lang> With a for loop: <lang java5>for(int i = 1024; i > 0;i /= 2 /*or i>>= 1*/){
System.out.println(i);
}</lang>
JavaScript
<lang javascript>var n = 1024; while (n>0) {
print(n); n/=2;
}</lang>
Logo
make "n 1024 while [:n > 0] [print :n make "n :n / 2]
Mathematica
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: <lang Mathematica>
i = 1024; While[i > 0, Print[i]; i = Floor[i/2]; ]
</lang>
MAXScript
a = 1024
while a > 0 do
(
print a
a /= 2
)
Make
NEXT=`expr $* / 2`
MAX=10
all: $(MAX)-n;
0-n:;
%-n: %-echo
@-make -f while.mk $(NEXT)-n MAX=$(MAX)
%-echo:
@echo $*
Invoking it
|make -f while.mk MAX=1024
Metafont
Metafont has no a while loop, but it can be "simulated" easily.
<lang metafont>a := 1024; forever: exitif not (a > 0);
show a; a := a div 2;
endfor</lang>
Modula-3
The usual module code and imports are omitted. <lang modula3>PROCEDURE DivBy2() =
VAR i: INTEGER := 1024;
BEGIN
WHILE i > 0 DO
IO.PutInt(i);
IO.Put("\n");
i := i DIV 2;
END;
END DivBy2;</lang>
Oberon-2
The usual module code and imports are ommited. <lang oberon2>PROCEDURE DivBy2*();
VAR i: INTEGER;
BEGIN
i := 1024; WHILE i > 0 DO Out.Int(i,0); Out.Ln; i := i DIV 2; END;
END DivBy2;</lang>
OCaml
<lang ocaml>let n = ref 1024;; while !n > 0 do
Printf.printf "%d\n" !n; n := !n / 2
done;;</lang>
But it is more common to write it in a tail-recursive functional style: <lang ocaml>let rec loop n =
if n > 0 then begin Printf.printf "%d\n" n; loop (n / 2) end
in loop 1024</lang>
Octave
<lang octave>i = 1024; while (i > 0)
disp(i) i = floor(i/2);
endwhile</lang>
The usage of the type int32 is not convenient, since the math is done floating point, then rounding to integer, so that 1/2 will be always 1 and never 0.
Pascal
<lang pascal> program divby2(output);
var
i: integer;
begin
i := 1024;
while i > 0 do
begin
writeln(i);
i := i div 2
end
end. </lang>
Perl
<lang perl>$n = 1024; while ($n > 0) {
print "$n\n"; $n >>= 1; # also acceptable: use integer; $n /= 2;
}</lang>
PHP
<lang php>$i = 1024; while ($i > 0) {
echo "$i\n"; $i >>= 1;
}</lang>
Pop11
lvars i = 1024;
while i > 0 do
printf(i, '%p\n');
i div 2 -> i;
endwhile;
Prolog
<lang prolog>while(0) :- !. while(X) :- write(X), nl, X1 is X // 2, while(X1).</lang>
Python
<lang python>n = 1024 while n > 0:
print n n //= 2</lang>
Ruby
<lang ruby>i = 1024 while i > 0 do
puts i i /= 2
end</lang> Ruby also has a "while" statement modifier: <lang ruby>i = 2048 puts i /=2 while i > 0</lang>
Scheme
<lang scheme> (do ((n 1024 (quotient n 2)))
((<= n 0)) (display n) (newline))</lang>
Slate
<lang slate> [| n | n: 1024.
[n isPositive] whileTrue:
[inform: number printString.
n: n // 2]] do
</lang>
Smalltalk
<lang smalltalk>number := 1024. [ number > 0 ] whileTrue:
[ Transcript print: number; nl. number := number // 2 ]</lang>
Standard ML
<lang sml>val n = ref 1024; while !n > 0 do (
print (Int.toString (!n) ^ "\n"); n := !n div 2
)</lang>
But it is more common to write it in a tail-recursive functional style: <lang sml>let
fun loop n =
if n > 0 then (
print (Int.toString n ^ "\n");
loop (n div 2)
) else ()
in
loop 1024
end</lang>
Tcl
<lang tcl>set i 1024 while {$i > 0} {
puts $i
set i [expr {$i / 2}]
}</lang>
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
V
1024 [0 >] [ dup puts 2 / >int ] while
Visual Basic .NET
Dim x = 1024
Do
Console.WriteLine(x)
x = x \ 2
Loop While x > 0
- Programming Tasks
- Iteration
- ActionScript
- Ada
- ALGOL 68
- AmigaE
- AutoHotkey
- AWK
- BASIC
- Befunge
- C
- C++
- C sharp
- ColdFusion
- Common Lisp
- D
- E
- FALSE
- Forth
- Factor
- Fortran
- Haskell
- Icon
- J
- Java
- JavaScript
- Logo
- Mathematica
- MAXScript
- Make
- Metafont
- Modula-3
- Oberon-2
- OCaml
- Octave
- Pascal
- Perl
- PHP
- Pop11
- Prolog
- Python
- Ruby
- Scheme
- Slate
- Smalltalk
- Standard ML
- Tcl
- UnixPipes
- V
- Visual Basic .NET