calvinlyp has asked for the wisdom of the Perl Monks concerning the following question:

hi all,

i am very new to perl programming. i got an error when running a perl script which uses certain numbers of perl modules.

below are the errors i got:

Use of uninitialized value in concatenation (.) or string at /usr/local/share/perl/5.10.0/Schedg/MyFiler.pm line 50, <FH> line 73260.

Use of uninitialized value in print at /usr/local/share/perl/5.10.0/Schedg/Filer.pm line 262, <FH> line 73260.

the files can be download from another forum: http://perlguru.com/gforum.cgi?post=38524;#38524

thanks.

Replies are listed 'Best First'.
Re: Errors in some perl modules
by aufflick (Deacon) on May 29, 2009 at 14:15 UTC
    Those messages are not errors, they're warnings. They are both warning you that variables are being used before they are set to anything. Imagine something like:

    my $var1;
my $var2;
$var1 = "Something";
print $var1 . $var2;

    [download]
    You can see that $var2 has not been set to anything. In Perl that is not an error, since an undefined value becomes a blank string in string context, but it is a pointer to sloppy coding or a mistake - hence why you get the warning when perl warnings are turned on.

    Update: Original had a typo where I said $var1 instead of $var2. Thanks to AnomalousMonk

[reply]
[d/l]

      You may also be using

      #!perl -w

      instead of

      #!perl
use warnings;

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      The first turns on warnings in modules as well as in the main program. The second ignores, for better or worse, warnings in any included modules.

      --MidLifeXis

      The tomes, scrolls etc are dusty because they reside in a dusty old house, not because they're unused. --hangon in this post

[reply]
[d/l]
[select]

      Those messages are not errors, they're warnings.

      Those messages are warnings and might not be errors.

      But in my experience, warnings almost always errors in Perl.

[reply]
        But in my experience, warnings almost always errors in Perl.

        Yes, if only because it is an error to get warnings and not heed them... ;-)

[reply]

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