Loops/Infinite
From Rosetta Code
You are encouraged to solve this task according to the task description, using any language you may know.
[edit] 4DOS Batch
@echo off
do forever
echo SPAM
enddo
[edit] 6502 Assembly
Specific OS/hardware routines for printing are left unimplemented.
InfiniteLoop LDX #0
PrintLoop: LDA MSG,x
JSR PrintAccumulator ;routine not implemented
INX
CPX #5
BNE PrintLoop
JMP InfiniteLoop
MSG .byte "SPAM", $0A
[edit] ActionScript
while (true) {
trace("SPAM");
}
[edit] Ada
loop
Put_Line("SPAM");
end loop;
[edit] ALGOL 68
DO
printf($"SPAM"l$)
OD
Or the classic "dynamic halt":
loop x:
printf($"SPAM"l$);
loop x
[edit] AmigaE
PROC main()
LOOP
WriteF('SPAM')
ENDLOOP
ENDPROC
[edit] AutoHotkey
Loop
MsgBox SPAM `n
[edit] AWK
BEGIN {
while(1) {
print "SPAM"
}
}
[edit] BASIC
Works with: QuickBasic version 4.5 Old-fashioned syntax:
WHILE 1
PRINT "SPAM"
WEND
Standard BASIC:
DO
PRINT "SPAM"
LOOP
Also
FOR i = 1 TO 10 STEP 0
PRINT "SPAM"
NEXT i
With classic (minimal) BASIC, the standard way to make an infinite loop would be:
10 PRINT "SPAM" 20 GOTO 10
[edit] Batch File
Using goto:
@echo off
:loop
echo SPAM
goto loop
Another variant which uses Windows NT's for statement:
Works with: Windows NT version 4 or later
for /l %%x in (1,0,2) do @echo SPAM
This essentially is a counted loop which starts at 1, increments by 0 and stops when the counter reaches 2.
[edit] Befunge
Because the 2-D code space is toroidal, all loops are infinite unless explicitly stopped with @.
55+"MAPS",,,,,
[edit] Brainf***
++++++++++[->++++++>++++++++>+<<<]>+++++>
[+++.---.<.>---.+++>.<]
[edit] C
while(1) puts("SPAM\n");
or
for(;;) puts("SPAM\n");
or
do { puts("SPAM\n"); } while(1);
[edit] C++
Translation of: C
while (true)
std::cout << "SPAM" << std::endl;
or
for (;;)
std::cout << "SPAM" << std::endl;
or
do
std::cout << "SPAM" << std::endl;
while (true);
[edit] C#
while (true)
{
Console.WriteLine("SPAM");
}
[edit] ColdFusion
This will result in a JRun Servlet Error and heap dump.
With tags:
<cfloop condition = "true NEQ false">
SPAM
</cfloop>
With script:
<cfscript>
while( true != false )
{
writeOutput( "SPAM" );
}
</cfscript>
[edit] Clojure
(loop [] (println "SPAM") (recur))
[edit] Common Lisp
(loop (write-line "SPAM"))
[edit] D
while(true) writefln("SPAM") ;
for(;;) writefln("SPAM") ;
l: writefln("SPAM"); goto l;
[edit] E
while (true) {
println("SPAM")
}
def f() {
println("SPAM")
f <- ()
}
f <- ()
The difference between these is that in the second, other activities can be interleaved with the loop; in the first, no other processing will occur in this vat.
[edit] Erlang
-module (main).
-export ([main/1]).
main(Any) ->
io:fwrite("SPAM~n",[]),
main(Any)
[edit] F#
while true do
printfn "SPAM"
done
let rec forever () : unit =
printfn "SPAM" ; forever ()
[edit] Factor
: spam ( -- ) "SPAM" print spam ;
: spam ( -- ) [ "SPAM" print t ] loop ;
[edit] FALSE
[1]["SPAM
"]#
[edit] Forth
: email begin ." SPAM" cr again ;
[edit] Fortran
Works with: Fortran version 90 and later
DO
WRITE(*,*) "SPAM"
END DO
Although deprecated GOTO is still available
10 WRITE(*,*) "SPAM"
GOTO 10
[edit] Go
package main
import "fmt"
func main() {
for {
fmt.Printf("SPAM\n")
}
}
[edit] Groovy
while (true) {
println 'SPAM'
}
[edit] Haskell
forever (putStrLn "SPAM")
[edit] HicEst
DO i = 1, 1E20 ! for i with 16 or more digits: i == i + 1 == loop infinite
WRITE() "SPAM"
ENDDO
[edit] Icon and Unicon
[edit] Icon
There are several ways to write infinite loops in Icon. The most straightforward would be with repeat.
procedure main()
repeat write("SPAM")
end
Alternately one could use one of these:
until &fail do write("SPAM") # always fails, needs succeed to break
...
while write("SPAM") # always succeeds, needs failure to break
...
every write(|"SPAM") # generator always succeeds, needs failure to break
...
while write(|"SPAM") # this is a common mistake that results in an endless loop
...
while write(1 to 5) # a clearer version of the same mistake that generates endless 1's
[edit] Unicon
This Icon solution works in Unicon.
[edit] IDL
while 1 do print,'SPAM'
[edit] Io
loop("SPAM" println)
[edit] J
-@:(][ 1!:2&2@('SPAM'"_)) (^:_) 1
Alternatively,
smoutput bind 'SPAM'^:1e99 ''
This second implementation relies on numeric inaccuracies in IEEE floating point notation. For example, 1+1e98 is exactly equal to 1e98. That said, 1e99 iterations would still be significantly longer than the practical life of any machine anyone would care to dedicate to this task.
[edit] Java
while(true){
System.out.println("SPAM");
}
for(;;){
System.out.println("SPAM");
}
[edit] JavaScript
for (;;) print("SPAM");
while (true) print("SPAM");
[edit] Joy
DEFINE loop == [1] swap while.
["SPAM\n" putchars] loop.
[edit] Lisaac
The "lisaac" compiler apparently doesn't like infinite loops. Using a static slot (variable) seems to be the only way to get away with "Recursivity without end (call_slot)." error.
- i : INTEGER;
i := 1;
{ i = 1 }.while_do {
"SPAM\n".print;
};
[edit] Logo
forever [print "SPAM]
[edit] Lua
while 1 do
print("SPAM")
end
[edit] M4
define(`spam',`SPAM
spam')
spam
[edit] Make
spam:
@echo SPAM
$(MAKE)
[edit] MAXScript
while true do print "SPAM\n"
[edit] Metafont
forever: message "SPAM"; endfor end
[edit] Modula-3
LOOP
IO.Put("SPAM\n");
END;
[edit] MOO
while (1)
player:tell("SPAM");
endwhile
[edit] MUMPS
FOR WRITE "SPAM",!
[edit] Objeck
while(true) {
"SPAM"->PrintLine();
};
[edit] OCaml
while true do
print_endline "SPAM"
done
or
let rec inf_loop() =
print_endline "SPAM";
inf_loop()
in
inf_loop()
Seen like this it looks like the "too much functional" danger when a "while" loop looks far simpler, but the functional loop may be useful to provide data to the next loop without using mutable variable.
[edit] Octave
while(1)
disp("SPAM")
endwhile
[edit] Oz
for do
{Show 'SPAM'}
end
[edit] Pascal
while true do
writeln('SPAM');
Alternatively:
repeat
writeln('SPAM')
until false;
[edit] Perl
print "SPAM\n" while 1;
[edit] Perl 6
Works with: Rakudo Star version 2010.08
loop {
say 'SPAM';
}
In addition, there are various ways of writing lazy, infinite lists in Perl 6:
print "SPAM\n" xx *; # repetition operator
print "SPAM\n", ~* ... *; # series operator
map {say "SPAM"}, ^Inf; # upto operator<lang>
=={{header|PHP}}==
<lang php>while(1)
echo "SPAM\n";
[edit] PicoLisp
(loop (prinl "SPAM"))
[edit] Pike
int main(){
while(1) write("SPAM\n");
}
[edit] PL/I
do forever;
put list ('SPAM'); put skip;
end;
[edit] Pop11
while true do
printf('SPAM', '%p\n');
endwhile;
[edit] PostScript
{}loop
[edit] PowerShell
for () {
"SPAM"
}
[edit] Prolog
repeat, write('SPAM'), nl, fail.
[edit] PureBasic
[edit] Repeat/Forever
Repeat
PrintN("SPAM")
ForEver
[edit] Goto
PrintIt:
PrintN("SPAM")
Goto PrintIt
[edit] Python
while 1:
print "SPAM"
Note: one can also use: "True" or any other non-false value. In Python the following values are false: 0, "" (empty string), (,) and {} and [] (empty tuples, dictionaries or lists), None (the special object), and the False object. Any non-empty collection or string or non-zero numeric value is considered "True". However, according to Python Wiki, for Python versions 2.3+ this variant is optimized by the interpreter and thus is the fastest.
[edit] R
Note that the default R Gui buffers outputs before pushing them to the screen. To see this run either run in terminal mode, right click on the GUI window and deselect "Buffered Output" prior to execution, or add a call to flush.console() in the loop.
repeat print("SPAM")
[edit] REBOL
forever [print "SPAM"]
[edit] REXX
do forever
say "SPAM"
end
[edit] Ruby
loop do
puts "SPAM"
end
[edit] Sather
class MAIN is
main is
loop
#OUT + "Spam\n";
end;
end;
end;
[edit] Scala
while (true)
println("SPAM")
[edit] Scheme
(do ()
(#f)
(display "SPAM")
(newline))
[edit] Slate
[inform: 'SPAM'] loop
[edit] Smalltalk
[ true ] whileTrue: [ 'SPAM' displayNl ]
[edit] SNOBOL4
loop output = "SPAM" :(loop)
end
[edit] SNUSP
@\>@\>@\>@\>++++++++++===!/ < < < < \
| | | \M=@@@@+@+++++# \.>.>.>.>./
| | \A=@@+@@@@+++#
| \P=@@+@@+@@+++#
\S=@@+@+@@@+++#
[edit] Standard ML
while true do
print "SPAM\n";
or
let
fun inf_loop () = (
print "SPAM\n";
inf_loop ()
)
in
inf_loop ()
end
Seen like this it looks like the "too much functional" danger when a "while" loop looks far simpler, but the functional loop may be useful to provide data to the next loop without using mutable variable.
[edit] SystemVerilog
program main;
initial forever $display("SPAM");
endprogram
[edit] Transact-SQL
WHILE 1=1 BEGIN
PRINT "SPAM"
END
[edit] Tcl
while true {
puts SPAM
}
# or
for {} 1 {} {
puts SPAM
}
[edit] TI-83 BASIC
There are a few ways to achieve this in TI-83 BASIC
:Goto 1
:Lbl 1
:Disp "SPAM"
:Goto 1
Another way is by using a While loop
:1→A
:While A = 1
:Disp "SPAM"
[edit] TI-89 BASIC
Loop
Disp "SPAM"
EndLoop
[edit] Trith
["SPAM" print] loop
[edit] UNIX Shell
Works with: Bourne Shell
Works with: Korn Shell
Works with: Public Domain Korn SHell
Works with: Almquist SHell
Works with: Debian Almquist SHell
Works with: Bourne Again SHell
Works with: Z Shell
while :; do echo SPAM; done
[edit] UnixPipes
yes SPAM
[edit] Unlambda
``ci``s``s`kr``s``s``s``s`k.S`k.P`k.A`k.Mii
[edit] V
true [
'SPAM' puts
] while
[edit] Vedit macro language
while (1) {
Message("Spam\n")
}
or:
do {
Message("Spam\n")
} while (1)
or:
for (;1;) {
Message("Spam\n")
}
"Nearly infinite" loop can be done by using constant ALL (=1073741824) as repeat count:
Repeat (ALL) {
Message("Spam\n")
}
[edit] Visual Basic
Do
Debug.Print("SPAM")
Loop
[edit] Visual Basic .NET
Platform: .NET Works with: Visual Basic .NET version 9.0+
Do
Console.WriteLine("SPAM")
Loop
