my $p = 7;  # Number of pigeon holes.
my $c = 12; # Number of cards
for my $s1 ( 1..$p ) {
    for my $s2 ( $s1..$p ) {
        for my $s3 ( $s2..$p ) {
            ... Need $c-$p loops

##</code><code>##

#!/usr/bin/perl -w
use strict;
use Algorithm::Loops 'NestedLoops';

my( $p, $c ) = @ARGV;
my $iter = NestedLoops(
    [ [ 1..$p ], ( sub { [ $_..$p ] } ) x ($c-$p-1) ],
);
my @s;
while( @s = $iter->() ) {
    my @p = (1) x $p;
    $p[$_-1]++ for @s;
    print "@p\n";
}