ikegami you are definitely a "blackbelt".

I expanded your code to show relevance to the OP's question.
Your map shows something that took me a long time to figure out,
how to return "nothing" from a map{}! 

use strict;
use warnings;

my @x = ("aaBxyz", "..Bxys", "bbxyzzy", "xxAx");

my @result = map { /^..(A|B)./ ? [ $1, $_ ] : () } @x;

# @result is a "2-d array", references to "rows of array"
# I swapped $1 and $_ because I thought the print out looked better

# Of course every map{} can be expressed as a for loop...

foreach my $row_ref (@result)
{
   print "@$row_ref\n";
}

=PRINTS:
B aaBxyz
B ..Bxys
A xxAx
=cut

[download]
I think this code is well past what the OP wanted.

ADDED: If the OP wants a subset of something, think GREP. If the OP wants to transform an input into something else, think MAP.

In reply to Re^2: do $n exist in grep? by Marshall
in thread do $n exist in grep? by misterperl

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