in reply to how to use join my array ?

I'm not sure that I fully understand the question, but ... is this something like what you're after- 
foreach my $z ( %abc) {
    push @ab, "-$z";    
}

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or possibly @ab = map { "-$_" } @ab; ?? 

foreach my $z (keys %abc) {
    push @ab, "-$z";    
}

[download]
or possibly @ab = map { "-$_" } keys %abc; ??

Update 1:

In fact I misunderstood the question so much as to provide complete and utter drivel as a reply - doh!!!

Update 2:

Attempted to provide a more meaningful and possibly half-sensible, reply.

A user level that continues to overstate my experience :-))

In Section Seekers of Perl Wisdom