use strict; use Data::Dumper; my @set = ('a'..'z'); my $size = 3; my @sample; my %seen; while( @sample < $size ){ my $elt; do{ $elt = int rand(@set); }while( $seen{$elt} ); push @sample, $set[$elt]; $seen{$elt}++; } print Dumper \@sample;