Question

I’m some trouble finding the problem with my program. Getting the error:

Use of uninitialized value in substitution (s///)

I realize this has been asked before, but that didn’t help me. I realize $1 might be unitialized, but I was wondering if you guys could help me figure out why?

Here’s the problem part of the code:

$one_match_ref->{'sentence'} = $1 if ($line =~ /^Parsing \[sent. \d+ len. \d+\]: \[(.+)\]/);
$one_match_ref->{'sentence'} =~ s/, / /g;

EDIT: I have declared the $one_match_ref->{'sentence'} like so:

my $sentence;
$one_match_ref = {
        chapternumber => $chapternumber_value,
        sentencenumber => $sentencenumber_value,
        sentence => $sentence, ##Get from parsed text: remove commas
        grammar_relation => $grammar_relation_value, ##Get from parsed text: split?
        arg1 => $argument1, ##Get from parsed text: first_dependencyword
        arg2 => $argument2 ##Get from parsed text: second_dependencyword
    };

But none of these variables have anything assigned to them.

My attempts:

A. If I put: if( defined (one_match_ref->{'sentence'})) after the s///, it works. But this is cumbersome, and seems to be avoiding the problem instead of fixing it.

The last time I used that fix, it was because my loop had an “off-by-one” error, I don’t think this is the case this time.

B. If I declare: my $sentence = ''; It prints, but with a lot of blank lines in between. How can I eliminate these?

EDIT: For interest and efficiency purposes: Is it better to use split to get what I want?

Thanks in advance for any help or advice. Let me know if you need an example of the file format.

Answer 1

Your code boils down to

my $sentence;
$one_match_ref = { sentence => $sentence };
() if ($line =~ /^Parsing \[sent. \d+ len. \d+\]: \[(.+)\]/);
$one_match_ref->{'sentence'} =~ s/, / /g;

You assign undef to $one_match_ref->{'sentence'}, then you try to remove the commas from it. That doesn’t make any sense, thus the warning.

Maybe you want

my $sentence;
$one_match_ref = { sentence => $sentence };
if ($line =~ /^Parsing \[sent. \d+ len. \d+\]: \[(.+)\]/) {
   $one_match_ref->{'sentence'} = $1;
   $one_match_ref->{'sentence'} =~ s/, / /g;
}