sub files_sort { my $first_number; my $second_number; if ($a =~ /(\d+)_(\d+)_duration_(\w+)_comptage_(\d+).txt$/){ $first_number = $1; } if ($b =~ /(\d+)_(\d+)_duration_(\w+)_comptage_(\d+).txt$/){ $second_number = $1; } $first_number <=> $second_number; }