Dear Monks,

I am chasing my off-by-one-error while solving this one and noticed a strange behavior (well, strange in my eyes :) ) of count++.

Here is a minimal example. As posted it prints 4 then 3. If I comment count++ and above the push and uncomment count++ below it prints 4 then 4, as I would have expected in the first case as well. This difference happens on the first occurrence only. Why?

Thanks in advance!

#!/perl
use strict;
use warnings;

my @AoA_1 =
(
     [ 2, 5, 9 ],
     [ 7, 6, 5 ],
     [ 1, 8, 3 ],
     [ 2, 5, 9 ],
     [ 7, 6, 5 ],
     [ 1, 8, 3 ],
);

my @AoA_2 =
(
     [ 9, 5, 2 ],
     [ 3, 6, 5 ],
     [ 0, 8, 3 ],
     [ 9, 5, 2 ],
     [ 3, 6, 5 ],
     [ 0, 8, 3 ], 
);
my $count;
my @test_array;
for my $n ( 0 .. $#AoA_1 )
{
     my @a1 = @{$AoA_1[$n]};
     my @a2 = @{$AoA_2[$n]};
     for my $i ( 0 .. $#a1 )
     {
          last if $a1[$i] < $a2[$i];
          next if $a1[$i] == $a2[$i];
           $count++ and 
           push @test_array, $n
            # and $count++
           and last
           if ( $a1[$i] > $a2[$i] );
     }
}
print $count, $/;
print scalar @test_array, $/;
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