Hi Monks!

I am running Perl v5.10.0 (built for x86_64-linux-thread-multi) and I have an issue with the "defined" function. I am not sure this is actually a fault, but it have worked in previously releases (unfortunately I don't know which).

The issue seems to happen when I've got a defined variable without a value, e.g. $var1 = "".

If I need to check if (one of) two variables are defined, I need to do that like this:

if (defined $var1 || defined $var2)
if (defined $var1 && defined $var2)

[download]

While I've previously been able to do it like this:

if (defined ($var1 || $var2))
if (defined ($var1 && $var2))

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Running the following fails for both OR and AND (test 1 and 3):

./test.pl ""
Test 1: NOK
Test 2: OK
Test 3: OK
Test 4: NOK

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When test.pl contains:

#!/usr/bin/perl

use strict;
use warnings;

for my $i (1 .. 4) {
    my $result = (&successfulValidation ($i))? "OK": "NOK";
    print "Test ", $i, ": ", $result, "\n";
}

sub successfulValidation {
    my $test = shift;

    if ($test == 1) {
        return defined ($ARGV[0] || $ARGV[1]);

    } elsif ($test == 2) {
        return defined $ARGV[0] || defined $ARGV[1];

    } elsif ($test == 3) {
        return defined ($ARGV[0] && $ARGV[1]);

    } elsif ($test == 4) {
        return defined $ARGV[0] && defined $ARGV[1];
    }
}

[download]

The following works just fine, though, so maybe the first (and only) variable to check can't be empty!?

./test.pl "" ""

Is it a bug that test 1 and test 3 fail? I mean, test 1 should have returned TRUE ($ARGV[0] was defined, although with an empty value) and test 3 should have returned "FALSE" ($ARGV[1] wasn't defined)? Maybe I am using "defined" in the wrong way!?

Many thanks in advance,

/Johan

In reply to "defined" function fails to evaluate expression; feature or fault? by w8lle

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