As others have pointed out, it is perl DWYM but exactly how does it do that? Well if you look at perl internals, a scalar value can be a string, an integer or a double (or another scalar). By context, it determines which value to use. In a numeric context (==), it will use one of the numeric (integer or double), in a string context, (eq), the string value.

Check this out:

#!/usr/bin/perl
use strict;
use warnings;
use Devel::Peek qw( Dump );

while (my $data = <DATA>) {
chomp $data;
print Dump( $data );
if ($data == 2){print "->got 2\n"}
}

print "Enter a 2\n";
my $input = <>;
print Dump( $input );
if ($input == 2){print "->got 2\n"}

__DATA__
1
2
3
4
[download]

-derby