I have to admit that your question does not make much sense to me. While there are hits on google for "binary sort", there doesn't seem to be a specific sorting method with this name. For instance the sorts who seem to have been called this include radix sort and binary insertion sort.

Anyway, here is a solution. I'm not going to say which one it is, I suggest you look into it yourself If you are tempted to hand this in to your teacher.

my $text="qwertyuiopasdfghjklzxcvbnm";

my @ltrs=split //,$text;

my ($val,@set,@unset)=(1);

while ($val) {
    push @{(ord($_) & $val) ? \@set : \@unset}, $_
        foreach @ltrs;
    $val <<= 1;
    @ltrs=( splice( @unset, 0, @unset ), splice( @set, 0, @set ) );
}

print join("-",@ltrs)."\n"
[download]

PS, please show a bit more effort in your posts. You'll get more support and feedback.

--- demerphq
my friends call me, usually because I'm late....