Equality and Perl
Now pay close attention, otherwise you'll end up posting an annoying question somewhere. This is a FAQ, as in a Frequently Asked Question.
The symbol = is an assignment operator, not
a comparison operator. Therefore:
if ($x = 10)is always true, because$xhas been assigned the value 10 successfully.if ($x == 10)compares the two values, which might not be equal.
So far we have been testing numbers, but there is more to life than numbers. There are strings too, and these need testing too.
$name = 'Mark';
$goodguy = 'Tony';
if ($name == $goodguy) {
print "Hello, Sir.\n";
} else {
print "Begone, evil peon!\n";
}
Something seems to have gone wrong here. Obviously Mark is different to Tony, so why does perl consider them equal?
Mark and Tony are equal -- numerically. We should be testing them as strings,
not as numbers. To do this, simply substitute == for
eq and everything will work as expected.
