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

If the line 40 in your posted code is the same as the line 40 in your script, that means that the marked line below is the source of the problem.

my @coursename;
my @c_arr ;# Course array

$mech->get($url);
$html = $mech->content();
$stream->get_tag("option");

while(my $token = $stream->get_token()){
  my $check = $token->[2]{name};
  if($check eq "dept[]"){
    while(my $token = $stream->get_token('option')){

      #### THE LINE BELOW TRIGGERED THE FOLLOWING MSG ####
      #### Use of uninitialized value in string eq ####

      if($token->[1] eq "option"){        
        $course_num = $token->[2]{value};
        $department = $stream->get_trimmed_text();
        $dep{ $course_num } = [$department];
      }
    }
  }
}
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If I have the right line, my guess is that the value of $token->[1] is undefined. To verify that $token->[1] (or any other variable you might care about) is undefined, you can insert code similar to the following code snippet.

   # value surrounded with <   > to make it easier to see
   # empty strings
   print STDERR "token[1]=<"
      .  (defined($token->[1]) ? $token->[1] : 'undef')
      . ">\n";
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In future posts, please mark the exact line mentioned in the error message along with the error message as I have done above. We have no way of knowing whether the line numbers of the posted code match the line numbers of your script and will be playing guessing games about where your error might be unless you mark it for us.

Best, beth

Right now I am getting this error... Use of uninitialized value in string eq at UOT_mississauga.pl line 40. I'm looking on google and here but I'm not sure how this error is happening. How would I work around this. How can token be uninitialized ?

use strict;
use warnings;
use WWW::Mechanize;
use HTML::TokeParser;
use Data::Dumper;
my $pre = '';
my $html;
my $htmll;
my $htmlll;
my $term = 20095; # 20095 = Summer;
my $year = 1 ;# 1st = 1 , 2nd = 2, 3rd = 3, 4th = 4
my $key;
my $v;
my $coursecode;
my $department;
my $prepre;
my $id;
my $stuff;
my $title;
my $description;
my $course_num;
my $check;
my $c_url = 'https://registrar.utm.utoronto.ca/student/timetable/new_t
+t_calprev.php?course='.$pre;
my $url = 'https://registrar.utm.utoronto.ca/student/timetable/index.p
+hp';
my $mech = WWW::Mechanize->new();
my $stream = HTML::TokeParser->new(\$html);
my $streamm = HTML::TokeParser->new(\$htmll);
my $streammm = HTML::TokeParser->new(\$htmlll);
my %dep;
my %newdep;
my @coursename;
my @c_arr ;# Course array

$mech->get($url);
$html = $mech->content();
$stream->get_tag("option");

while(my $token = $stream->get_token()){

    if($token->[0] eq "S" && $token->[2]{name} eq "dept/[/]"){
    print Dumper $token;
        while(my $token = $stream->get_token()){
        if($token->[1] eq "option"){        
            $course_num = $token->[2]{value};
            $department = $stream->get_trimmed_text();
            $dep{ $course_num } = [$department];
            }
        }
    }
}

while (($key, $v) = each(%dep)){
    $coursecode = $key;
    $coursecode =~ s/\s//g;
    $department = $v;
    
    $mech->get($url);
        $mech->submit_form(
            fields=>{
                session=>$term,
                'yos[]'=>$year,
                'dept[]'=>$key,    
                },
            );
        $htmll = $mech->content();
        
        ### PRINTS HERE
        
        while(my $tokenn = $streamm->get_token()){    
        ### DOESNT WANT TO PRINT HERE
    
            if($tokenn->[1] eq "a" && $tokenn->[2]{name}){
                push(@coursename,$tokenn->[2]{name});
                $prepre = $tokenn->[2]{name};
                $newdep{ $department } = $coursecode;
            }    
        }        
}
while (($id, $stuff) = each(%newdep)){
    print "Id:$id Stuff:$stuff .\n ";
    }

sub print_csv{
    foreach(@coursename){
    $pre = $_;
    print $pre;
    $mech->get($c_url);
    $htmlll = $mech->content();
    $streammm->get_tag("p");
    $title = $streammm->get_trimmed_text();
    $title =~ s/($coursecode).//g;
    $streammm->get_tag("/p");
    $description = $streammm->get_trimmed_text();
    #print '"'.$prefix.'";"'.$title.'";"'.$description.'";"'.$departme
+nt.'"'."\n";
    }
    }
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That start element you are processing doesn't have a "name" attribute, so $token->[2]{name} is undefined.

Then shouldn't the compiler just skip over that line ? It's an if statement. I'm iterating through all the tags until one of them meets my conditions. I don't understand how this is bad code practice. I'm not able to know if a condition is met other wise. Why have if available to use in the first place right ?

Can't use string ("") as a HASH ref while "strict refs" in use at 7603
+86.pl
        line 40 (#1)
    (F) Only hard references are allowed by "strict refs".  Symbolic
    references are disallowed.  See perlref.
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