Loops/Break
You are encouraged to solve this task according to the task description, using any language you may know.
Show a loop which prints random numbers (each number newly generated each loop) from 0 to 19 (inclusive). If a number is 10, stop the loop after printing it, and do not generate any further numbers. Otherwise, generate and print a second random number before restarting the loop. If the number 10 is never generated as the first number in a loop, loop forever.
Ada
<lang Ada>with Ada.Text_IO; use Ada.Text_IO; with Ada.Numerics.Discrete_Random;
procedure Test_Loop_Break is
type Value_Type is range 1..20; package Random_Values is new Ada.Numerics.Discrete_Random (Value_Type); use Random_Values; Dice : Generator; A, B : Value_Type;
begin
loop
A := Random (Dice);
Put_Line (Value_Type'Image (A));
exit when A = 10;
B := Random (Dice);
Put_Line (Value_Type'Image (B));
end loop;
end Test_Loop_Break;</lang>
AutoHotkey
<lang AutoHotkey>Loop {
Random, var, 0, 19 output = %output%`n%var% If (var = 10) Break Random, var, 0, 19 output = %output%`n%var%
} MsgBox % output</lang>
BASIC
<lang qbasic>do
a = int(rnd * 20) print a if a = 10 then exit loop 'EXIT FOR works the same inside FOR loops b = int(rnd * 20) print b
loop</lang>
C
<lang c>#include <stdlib.h>
- include <time.h>
- include <stdio.h>
int main() {
int a, b;
srand(time(NULL));
while (1) {
a = rand() % 20; /* not exactly uniformly distributed, but doesn't matter */
printf("%d\n", a);
if (a == 10) break;
b = rand() % 20; /* not exactly uniformly distributed, but doesn't matter */
printf("%d\n", b);
}
return 0;
}</lang>
C#
<lang csharp>class Program {
static void Main(string[] args)
{
Random random = new Random();
while (true)
{
int a = random.Next(20);
Console.WriteLine(a);
if (a == 10)
break;
int b = random.Next(20)
Console.WriteLine(b);
}
Console.ReadLine();
}
}</lang>
Chef
"Liquify" is now depreciated in favor of "Liquefy", but my interpreter/compiler (Acme::Chef) works only with "Liquify" so that's how I'm leaving it. At least it'll work no matter which version you use.
<lang Chef>Healthy Vita-Sauce Loop - Broken.
Makes a whole lot of sauce for two people.
Ingredients. 0 g Vitamin A 1 g Vitamin B 2 g Vitamin C 3 g Vitamin D 4 g Vitamin E 5 g Vitamin F 6 g Vitamin G 7 g Vitamin H 8 g Vitamin I 9 g Vitamin J 10 g Vitamin K 11 g Vitamin L 12 g Vitamin M 13 g Vitamin N 14 g Vitamin O 15 g Vitamin P 16 g Vitamin Q 17 g Vitamin R 18 g Vitamin S 19 g Vitamin T 20 g Vitamin U 21 g Vitamin V 22 g Vitamin W 32 g Vitamin X 24 g Vitamin Y 25 g Vitamin Z
Method. Liquify Vitamin X. Put Vitamin N into 1st mixing bowl. Fold Vitamin Y into 1st mixing bowl. Liquify Vitamin Y. Clean 1st mixing bowl. Put Vitamin K into 1st mixing bowl. Fold Vitamin Z into 1st mixing bowl. Liquify Vitamin Z. Clean 1st mixing bowl. Put Vitamin Y into 4th mixing bowl. Put Vitamin Z into 4th mixing bowl. Pour contents of the 4th mixing bowl into the 2nd baking dish. Put Vitamin A into 2nd mixing bowl. Put Vitamin B into 2nd mixing bowl. Put Vitamin C into 2nd mixing bowl. Put Vitamin D into 2nd mixing bowl. Put Vitamin E into 2nd mixing bowl. Put Vitamin F into 2nd mixing bowl. Put Vitamin G into 2nd mixing bowl. Put Vitamin H into 2nd mixing bowl. Put Vitamin I into 2nd mixing bowl. Put Vitamin J into 2nd mixing bowl. Put Vitamin K into 2nd mixing bowl. Put Vitamin L into 2nd mixing bowl. Put Vitamin M into 2nd mixing bowl. Put Vitamin N into 2nd mixing bowl. Put Vitamin O into 2nd mixing bowl. Put Vitamin P into 2nd mixing bowl. Put Vitamin Q into 2nd mixing bowl. Put Vitamin R into 2nd mixing bowl. Put Vitamin S into 2nd mixing bowl. Put Vitamin T into 2nd mixing bowl. Verb the Vitamin V. Mix the 2nd mixing bowl well. Fold Vitamin U into 2nd mixing bowl. Put Vitamin U into 3rd mixing bowl. Remove Vitamin K from 3rd mixing bowl. Fold Vitamin V into 3rd mixing bowl. Put Vitamin X into 1st mixing bowl. Put Vitamin V into 1st mixing bowl. Verb until verbed. Pour contents of the 1st mixing bowl into the 1st baking dish.
Serves 2.</lang>
Clojure
<lang lisp>(loop [[a b & more] (repeatedly #(rand-int 20))]
(println a) (when-not (= 10 a) (println b) (recur more)))</lang>
Common Lisp
<lang lisp>(loop
(setq a (random 20))
(print a)
(if (= a 10)
(return))
(setq b (random 20))
(print b))</lang>
D
Using Mersenne twister;
<lang D>import tango.io.Stdout; import tango.math.random.Twister;
void main() {
alias Twister.instance r; uint x;
while (~1) {
x = r.natural(20);
Stdout (x) (" ");
if (x == 10) break;
Stdout (r.natural(20)).newline;
}
}</lang>
E
<lang e>while (true) {
def a := entropy.nextInt(20)
print(a)
if (a == 10) {
println()
break
}
println(" ", entropy.nextInt(20))
}</lang>
Factor
Using with-return:
<lang factor>[
[ 20 random [ . ] [ 10 = [ return ] when ] bi 20 random . t ] loop
] with-return</lang>
Idiomatic Factor: <lang factor>[ 20 random [ . ] [ 10 = not ] bi 20 random . ] loop</lang>
Forth
<lang forth>include random.fs
- main
begin 20 random dup . 10 <> while 20 random . repeat ;
\ use LEAVE to break out of a counted loop
- main
100 0 do i random dup . 10 = if leave then i random . loop ;</lang>
Fortran
<lang fortran>program Example
implicit none
real :: r integer :: a, b
do
call random_number(r)
a = int(r * 20)
write(*,*) a
if (a == 10) exit
call random_number(r)
b = int(r * 20)
write(*,*) b
end do
end program Example</lang>
Haskell
<lang haskell>import Control.Monad import System.Random
loopBreak n k = do
r <- randomRIO (0,n) print r unless (r==k) $ do print =<< randomRIO (0,n) loopBreak n k</lang>
Use: <lang haskell>loopBreak 19 10</lang>
HicEst
<lang hicest>1 DO i = 1, 1E20 ! "forever"
a = INT( RAN(10, 10) )
WRITE(name) a
IF( a == 10) GOTO 10
b = INT( RAN(10, 10) )
WRITE(name) b
ENDDO
10
END</lang>
Icon
<lang Icon>procedure main()
while 10 ~= writes(?20-1) do write(", ",?20-1)
end</lang> Notes:
- For any positive integer i, ?i produces a value j where 1 <= j <= i
- Although this can be written with a break (e.g. repeat expression & break), there is no need to actually use one. (And it's ugly).
- Programmers new to Icon/Unicon need to understand that just about everything returns values including comparison operators, I/O functions like write/writes.
- This program will perform similarly but not identically under Icon and Unicon because the random operator ?i behaves differently. While both produce pseudo-random numbers a different generator is used. Also, the sequence produced by Icon begins with the same seed value and is repeatable whereas the sequence produced by Unicon does not.
J
<lang j>loopexample=: verb define
while. 1 do. smoutput n=. ?20 if. 10=n do.return.end. smoutput ?20 end.
)</lang>
Java
<lang java>import java.util.Random;
Random rand = new Random(); while(true){
int a = rand.nextInt(20); System.out.println(a); if(a == 10) break; int b = rand.nextInt(20); System.out.println(b);
}</lang>
JavaScript
<lang javascript>for (;;) {
var a = Math.floor(Math.random() * 20); print(a); if (a == 10) break; a = Math.floor(Math.random() * 20); print(a);
}</lang>
The print() function is available in the Rhino JavaScript shell.
Lisaac
<lang Lisaac>Section Header
+ name := TEST_LOOP_BREAK;
Section Public
- main <- (
+ a, b : INTEGER;
`srand(time(NULL))`;
{
a := `rand()`:INTEGER % 20; // not exactly uniformly distributed, but doesn't matter
a.print;
'\n'.print;
a == 10
}.until_do {
b := `rand()`:INTEGER % 20; // not exactly uniformly distributed, but doesn't matter
b.print;
'\n'.print;
}
);</lang>
Lua
<lang lua>repeat
k = math.random(19) print(k) if k == 10 then break end print(math.random(19)
until false</lang>
M4
<lang M4>define(`randSeed',141592653)dnl define(`setRand',
`define(`randSeed',ifelse(eval($1<10000),1,`eval(20000-$1)',`$1'))')dnl
define(`rand_t',`eval(randSeed^(randSeed>>13))')dnl define(`random',
`define(`randSeed',eval((rand_t^(rand_t<<18))&0x7fffffff))randSeed')dnl
dnl define(`loopbreak',`define(`a',eval(random%20))`a='a ifelse(a,10,`',`define(`b',eval(random%20))`b='b loopbreak')')dnl dnl loopbreak</lang>
Output:
a=17 b=3 a=0 b=15 a=10
Modula-3
<lang modula3>MODULE Break EXPORTS Main;
IMPORT IO, Fmt, Random;
VAR a,b: INTEGER;
BEGIN
WITH rand = NEW(Random.Default).init() DO
LOOP
a := rand.integer(min := 0, max := 19);
IO.Put(Fmt.Int(a) & "\n");
IF a = 10 THEN EXIT END;
b := rand.integer(min := 0, max := 19);
IO.Put(Fmt.Int(b) & "\n");
END;
END;
END Break.</lang>
MOO
<lang moo>while (1)
a = random(20) - 1; player:tell(a); if (a == 10) break; endif b = random(20) - 1; player:tell(b);
endwhile</lang>
OCaml
<lang ocaml># Random.self_init();; - : unit = ()
- while true do
let a = Random.int 20 in print_int a; print_newline(); if a = 10 then raise Exit; let b = Random.int 20 in print_int b; print_newline() done;;
15 18 2 13 10 Exception: Pervasives.Exit.</lang>
Octave
<lang octave>while(1)
a = floor(unifrnd(0,20, 1)); disp(a) if ( a == 10 ) break endif b = floor(unifrnd(0,20, 1)); disp(b)
endwhile</lang>
Oz
We can implement this either with recursion or with a special type of the for-loop. Both can be considered idiomatic. <lang oz>for break:Break do
R = {OS.rand} mod 20
in
{Show R}
if R == 10 then {Break}
else {Show {OS.rand} mod 20}
end
end</lang>
Perl
<lang perl>while (1) {
my $a = int(rand(20));
print "$a\n";
if ($a == 10) {
last;
}
my $b = int(rand(20));
print "$b\n";
}</lang>
Perl 6
<lang perl6>loop {
my $n = (0..19).pick; say $n; last if $n == 10; say (0..19).pick;
}</lang>
PHP
<lang php>while (true) {
$a = rand(0,19);
echo "$a\n";
if ($a == 10)
break;
$b = rand(0,19);
echo "$b\n";
}</lang>
PicoLisp
Literally: <lang PicoLisp>(use R
(loop
(println (setq R (rand 1 19)))
(T (= 10 R))
(println (rand 1 19)) ) )</lang>
Shorter: <lang PicoLisp>(until (= 10 (println (rand 1 19)))
(println (rand 1 19)) )</lang>
PL/I
<lang PL/I> do forever;
k = random()*19; put (k); if k = 10 then leave; k = random()*19; put skip list (k);
end; </lang>
Pike
<lang pike>int main(){
while(1){
int a = random(20);
write(a + "\n");
if(a == 10){
break;
}
int b = random(20);
write(b + "\n");
}
}</lang>
PowerShell
<lang powershell>$r = New-Object Random for () {
$n = $r.Next(20)
Write-Host $n
if ($n -eq 10) {
break
}
Write-Host $r.Next(20)
}</lang>
PureBasic
<lang PureBasic>If OpenConsole()
Repeat
a = Random(19)
PrintN(Str(a))
If a = 10
Break
EndIf
b = Random(19)
PrintN(Str(b))
PrintN("")
ForEver
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit") Input() CloseConsole()
EndIf</lang>
Python
<lang python>import random
while True:
a = random.randrange(20)
print a
if a == 10:
break
b = random.randrange(20)
print b</lang>
R
<lang R>sample0to19 <- function() sample(0L:19L, 1,replace=TRUE) repeat {
result1 <- sample0to19()
if (result1 == 10L)
{
print(result1)
break
}
result2 <- sample0to19()
cat(result1, result2, "\n")
}</lang>
REBOL
<lang REBOL>REBOL [ Title: "Loop/Break" Author: oofoe Date: 2009-12-19 URL: http://rosettacode.org/wiki/Loop/Break ]
random/seed 1 ; Make repeatable.
- random/seed now ; Uncomment for 'true' randomness.
r20: does [(random 20) - 1]
forever [ prin x: r20 if 10 = x [break] print rejoin [" " r20] ] print ""</lang>
Output:
14 11 19 15 6 11 12 11 3 14 10
REXX
<lang rexx>do forever
a = random(19) say a if a = 10 then leave b = random(19) say b
end</lang>
Ruby
<lang ruby>loop do
a = rand(20)
puts a
if a == 10
break
end
b = rand(20)
puts b
end</lang>
Scala
A break library method is available in Scala 2.8 but not 2.7
<lang Scala> import scala.util.Random
val rand = new Random var doNext = true
while(doNext) {
val first = rand.nextInt(20) println(first)
if (first != 10) {
val second = rand.nextInt(20)
println(second)
} else {
doNext = false
}
} </lang>
Suneido
<lang Suneido>forever
{
Print(i = Random(20))
if i is 10
break
Print(i = Random(20))
}
</lang>
TI-89 BASIC
<lang ti89b>Local x Loop
rand(20)-1 → x Disp x © new line and text If x = 10 Then Exit EndIf Output 64, 50, rand(20)-1 © paint text to the right on same line
EndLoop</lang>
Tcl
<lang tcl>while true {
set a [expr int(20*rand())]
puts $a
if {$a == 10} {
break
}
set b [expr int(20*rand())]
puts $b
}</lang>
Unicon
See Icon.
VBScript
Implementation
Based on BASIC version. Demonstrates breaking out of do/loop and for/next (Exit is good for getting out of functions and subs as well)
<lang vb> do a = int( rnd * 20) wscript.stdout.write a if a = 10 then exit do b = int( rnd * 20 ) wscript.echo vbnullstring,b loop
dim i for i = 1 to 100000 a = int( rnd * 20) wscript.stdout.write a if a = 10 then exit for b = int( rnd * 20 ) wscript.echo vbnullstring,b next </lang>