Warnings on equality operators

operators, perl, warnings

Solution

Perl will be try to convert a scalar to the type required by the context where it is used.

There is a valid conversion from any scalar type to a string, so this is always done silently.

Conversion to a number is also done silently if the string passes a `looks_like_number` test (accessible through `Scalar::Util`). Otherwise a warning is raised and a 'best guess' approximation is done anyway.

my $string = '9';
if ( $string == 9 ) { print "YES" };

Converts the string silently to integer 9, the test succeeds and `YES` is printed.

my $string = '9,8';
if ( $string == 9 ) { print "YES" };

Raises the warning `Argument "9,8" isn't numeric in numeric eq (==)`, converts the string to integer 9, the test succeeds and `YES` is printed.

To my knowledge it has always been this way, at least since v5.0.

Problem

Has something changed in Perl or has it always been this way, that examples like the second (`$number eq 'a'`) don't throw a warning? ``` #!/usr/bin/env perl use warnings; use 5.12.0; my $string = 'l'; if ($string == 0) {}; my $number = 1; if ($number eq 'a') {}; # Argument "l" isn't numeric in numeric eq (==) at ./perl.pl line 6. ```

Original source