Loop structures
AppleScript
repeat-until
set i to 5 repeat until i is less than 0 set i to i - 1 end repeat
repeat --endless loop end repeat
repeat-with
repeat with i from 1 to 20
--do something
end repeat
set array to {1,2,3,4,5}
repeat with i in array
display dialog i
end repeat
C
while
Compiler: GCC 4.1.2
int main (int argc, char ** argv) {
int condition = 1;
while ( condition ) {
// Do something
// Don't forget to change the value of condition.
// If it remains nonzero, we'll have an infinite loop.
}
}
C++
Run-Time Control Structures
for
Compiler: GCC 3.3.4
#include <iostream>
int main()
{
int i = 1;
// Loops forever:
for(; i == 1;)
std::cout << "Hello, World!\n";
}
do-while
Compiler: GCC 4.1.2
int main (void) {
int condition = 1;
do {
// Do something
// Don't forget to change the value of condition.
// If it remains nonzero, we'll have an infinite loop.
} while ( condition );
}
Run-Time Control Structures
while
Compiler: GCC 4.1.2
int main (void) {
int condition = 1;
while ( condition ) {
// Do something
// Don't forget to change the value of condition.
// If it remains nonzero, we'll have an infinite loop.
}
}
do-while
Compiler: GCC 4.1.2
int main (void) {
int condition = 1;
do {
// Do something
// Don't forget to change the value of condition.
// If it remains nonzero, we'll have an infinite loop.
} while ( condition );
}
Java
while
while(true)
{
foo();
}
do-while
do
{
foo();
}
while (true)
for
for(int i = 0; i < 5; i++)
{
foo();
}
foreach
Platform: J2SE 1.5.0
Object[] objects;
// ...
for (Object current : objects[]) {
// ...
}
int[] numbers;
// ...
for (int i : numbers) {
// ...
}
JavaScript
while
while(true)
{
foo();
}
for
for(var i = 0; i < 5; i++)
{
foo();
}
foreach
//iterate through properties of an object as if through a collection
var obj = {prop1:"a",prop2:"b",prop3:"c"};
for (var key in obj)
alert(obj[key]);
Pascal
while
Compiler: Turbo Pascal 7.0
WHILE condition1 DO
BEGIN
procedure1;
procedure2;
END;
repeat-until
Compiler: Turbo Pascal 7.0
REPEAT procedure1; procedure2; UNTIL condition1;
for
Compiler: Turbo Pascal 7.0
FOR counter=1 TO 10 DO
BEGIN
procedure1;
procedure2;
END;
Perl
while
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my $condition1 = 0;
while ( $condition1 ) {
# Do something.
# Remember to change the value of condition1 at some point.
}
do-while
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my $condition1 = 0;
do {
# Do something.
# Remember to change the value of condition1 at some point.
} while ( $condition1 );
until
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my $condition1 = 1;
until ( $condition1 ) {
# Do something.
# Remember to change the value of condition1 at some point.
}
do-until
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my $condition1 = 1;
do {
# Do something.
# Remember to change the value of condition1 at some point.
} until ( $condition1 );
for
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my $limit = 5;
for ( my $iterator = 0; $iterator < $limit; $iterator++ ) {
# Do something
}
# for-variant, implicit iteration
for (0..$limit) {
# Do something
}
do_something() for 0..$limit;
foreach
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my @numbers = (1, 2, 3);
my %names = (first => "George", last => "Jetson");
foreach my $number (@numbers) {
# Do something with $number
}
foreach my $key (keys %names) {
# Do something with $key (values are accessible as %names{$key} )
}
map
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my @numbers = (1, 2, 3);
my @target;
@target = map {
# Do something with $_
} @numbers;
@target = map($_ + 1, @numbers);
sub a_sub {
# Do something with $_
}
@target = map a_sub @numbers;
grep
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my @people = qw/Bobbie Charlie Susan/;
my @target;
@target = grep {
# Discriminate based on $_
} @people;
# Feed grep into map, this picks out elements 1, 3, 5, etc.
@target = map($people[$_], grep($_ & 1, 0..$#people));
# Pick out the diminutive names
@target = grep(/ie$/, @people);
sub a_sub {
# Do something with $_, and return a true or false value
}
@target = grep a_sub @people;
PHP
while
while(ok()) {
foo();
bar();
baz();
}
for
for($i = 0; $i < 10; ++$i) {
echo $i;
}
foreach
foreach(range(0, 9) as $i) {
echo $i;
}
Python
with
Interpreter: Python 2.5
foo could for example open a file or create a lock or a database transaction:
with foo() as bar: baz(bar)
while
while ok():
foo()
bar()
baz()
else:
# break was not called
quux()
for
for i in range(10):
print i
else:
# break was not called
foo()
Ruby
while
while true do foo end
for
for i in [0..4] do foo end
SmallTalk
whileTrue/whileFalse
x := 0.
[ x < 100 ]
whileTrue: [ x := x + 10.].
[ x = 0 ]
whileFalse: [ x := x - 20.].