Question

I’m just trying to check if a string is equal to “%2B”, and if it does I change it to “+”.
The problem lies in comparison.

if ($lastItem == "%2B"){
   $lastItem = "+";
}

When $lastItem is something completely different (like “hello”), it will still go into the statement. I’ve been wracking my brain and I just can’t tell where I’ve gone wrong. Does %2B have some special meaning? I’m very new to perl.

Thanks

Answer 1

You need to use eq when comparing strings, or perl will try to convert the string to a number (which will be 0), and you will find such oddities as "a" == 0 to evaluate true. And when comparing two strings, you will of course effectively get if (0 == 0), which is the problem you are describing.

if ($lastItem eq "%2B") {

It is important to note that if you had used use warnings, this problem would have been easier to spot, as this one-liner will demonstrate:

$ perl -wE 'say "yes" if ("foo" == "bar")'
Argument "bar" isn't numeric in numeric eq (==) at -e line 1.
Argument "foo" isn't numeric in numeric eq (==) at -e line 1.
yes