Re^2: sorting files

[GrandFather]

I'd rewrite the sub as:

sub files_sort {
    my $re = qr/(\d+)_\d+_duration_\w+_comptage_\d+.txt$/;
    my $first_number = $a =~ $re ? $1 : -1;
    my $second_number = $b =~ $re ? $1 : -1;

    return $first_number <=> $second_number;
}

which is slightly more compact and deals better with bad matches by avoiding comparing undefined values. Explicit returns are good too.