use strict;
use warnings;

my $a = 10;
my $b = 10;

#IMHO: $a-- should finish the current operation and then -1
if ($a == $b--)
{
	print "\n T1";
	
}

$b=10;
#IMHO: --$a should -1 first and continute with current operation , i.e if compare
if ($a == --$b)
{
    print "\n T2";
}

#ENV: #Active Perl 5.20, Windows 7, x64 

#Output
# T2