use strict; use Algorithm::Loops qw( NestedLoops ); my $bits= 8; my $ones= 5; my $iter= NestedLoops( [ [ 0 .. $bits-1 ], ( sub { [ 1+$_[-1] .. $bits-1 ] } ) x ($ones-1), ], ); my @ones; while( @ones= $iter->() ) { my @bits= (0) x $bits; @bits[@ones]= (1) x $ones; print join '', @bits, $/; }