period in strings

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

Hi! i'm relatively new to perl and keep getting this warning:

Use of uninitialized value in string eq at test.pl line 40.

foreach my $key (@keys) {
if (($key->{'att'}->{'for'} eq 'node') && ($key->{'att'}->{'yfiles.type'} eq 'nodegraphics')){ #line 40 here
$nodeD = $key->{'att'}->{'id'};
} elsif (($key->{'att'}->{'for'} eq 'edge') && ($key->{'att'}->{'yfiles.type'} eq 'edgegraphics')){
$edgeD = $key->{'att'}->{'id'};
}
}
i wonder if it is the period in the 'yfiles.type' that is causing the warning and how i can get rid of it?

Comment on period in strings

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Re: period in strings by kennethk (Abbot) on Apr 27, 2010 at 21:54 UTC
The issue is not the period, per se, but that the nested hash structure is uninitialized for either `$key->{'att'}->{'for'}` or `$key->{'att'}->{'yfiles.type'}`. I would suggest you use Data::Dumper to examine your `@keys` structure before you reach the loop to see if the data content matches your expectations. Inserting the following before your foreach loop should suffice: `use Data::Dumper; print Dumper \@keys;` [download] On a side note, please wrap posted code in `<code>` tags to maintain formatting, as per Writeup Formatting Tips or Markup in the Monastery. And welcome to the Monastery.	[reply] [d/l] [select]
Re: period in strings by apl (Monsignor) on Apr 27, 2010 at 22:24 UTC
You never need to "wonder". Googling Perl uninitialized value would have pointed you towards something like this.	[reply]
Re: period in strings by doug (Pilgrim) on Apr 28, 2010 at 12:55 UTC
Ouch, That is ugly. Next time try something like `my %field = %{ $key->{att} };` or maybe `my $for = $key->{att}->{'for'}; my $type = $key->{att}->{yfiles.type};` [download] to reduce the amount of dereferencing. It is really easy to misread all that stuff. - doug	[reply] [d/l] [select]