String compare in Perl with "eq" vs "=="

string perl
hari picture hari · Dec 26, 2012 · Viewed 314.6k times · Source

I am (a complete Perl newbie) doing string compare in an if statement:

If I do following:

if ($str1 == "taste" && $str2 == "waste") { }

I see the correct result (i.e. if the condition matches, it evaluates the "then" block). But I see these warnings:

Argument "taste" isn't numeric in numeric eq (==) at line number x.
Argument "waste" isn't numeric in numeric eq (==) at line number x.

But if I do:

if ($str1 eq "taste" && $str2 eq "waste") { }

Even if the if condition is satisfied, it doesn't evaluate the "then" block.

Here, $str1 is taste and $str2 is waste.

How should I fix this?

Answer

PSIAlt picture PSIAlt · Dec 26, 2012

First, eq is for comparing strings; == is for comparing numbers.

Even if the "if" condition is satisfied, it doesn't evaluate the "then" block.

I think your problem is that your variables don't contain what you think they do. I think your $str1 or $str2 contains something like "taste\n" or so. Check them by printing before your if: print "str1='$str1'\n";.

The trailing newline can be removed with the chomp($str1); function.

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