The code shown has no output: it simply overwrites the value of $pair with a new value on each iteration of the nested loops. So, if you add the statement say $pair; after both loops have finished, of course you see only the last value of $pair, which happens to be YY.

To get all the values, you need to move the say statement into the inner loop:

use strict;
use warnings;
use feature qw( say );

my @aa = qw(A C D E F G H I K L M N P Q R S T V W Y);
my $pair;

for my $n1 (@aa)
{
    for my $n2 (@aa)
    {
        $pair = $n1 . $n2;    
        say $pair;
    }
}

[download]

As an alternative, you could store the pairs in an array and output them after the loops have finished:

use strict;
use warnings;
use feature qw( say );

my @aa = qw(A C D E F G H I K L M N P Q R S T V W Y);
my @pairs;

for my $n1 (@aa)
{
    for my $n2 (@aa)
    {
        push @pairs, $n1 . $n2;
    }
}

say for @pairs;

[download]

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re^2: doubts on Perl hash by Athanasius
in thread doubts on perl Hash by raulgh5

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