in reply to How to get specific hash elements?

If I understand you correctly, you should be able to use $hash{$variable_name}{'fixed name'} both as an lvalue or an rvalue.

Try this (tested):

use strict;
my %hash;
$hash{'test1'}{'fixed name'} = 42;
my $variable_name = 'test1';
print $hash{$variable_name}{'fixed name'};
print "\n";

[download]

When executed, it prints 42.

Replies are listed 'Best First'.
Re^2: How to get specific hash elements?
by talking_walnut (Initiate) on May 14, 2007 at 15:56 UTC
    Tried this format and it's giving me "Use of uninitialized value in print at ./testScript.pl line 10". My hash is actually of the form: 
    $VAR1 = 'Variable_name1                         ';
$VAR2 = {
          'Fixed_name1     ' => {
                            'value    ' => undef
                          },
          'Fixed_name2   ' => {
                            'value    ' => undef
                          }
        };
$VAR3 = 'Variable_Name2                                    ';
$VAR4 = {
          'Fixed_name1       ' => {
                            'value    ' => undef
                          },
          'Fixed_name2   ' => {
                            'value    ' => undef
                          }
        };

    [download]
    I don't know why it's pointing the values to undefined at the end. "value" is the thing I'm looking for. Thanks for the help guys. Been stuck on this for a few days and it's beginning to annoy me
[reply]
[d/l]

      What's with all the white space at the end of your keys? That's going to cause problems: 'Fixed_name1     ' does not equal 'Fixed_name1'.

      -derby
[reply]
[d/l]
[select]
        I figured that alright and tried the code with all the spaces but it didn't make any difference. I'm pulling the data from a database that's why the white space is there. That's also how it's being assigned the undef value although I don't know why. Here's the structure of the code that's doing that: 
        my %ret;
if ( defined( $rv ) and @$rv )
        {
                map { %{$ret{$$_{name}}->{$$_{project}}={$$_{result}}}
+} @$rv;
        }
return %ret;

        [download]

        Update: I finally managed to get this working the way I wanted. Just thought I'd post how I did it in case it's useful to someone else in the future and wanted to say thanks to everyone that took the time to reply to me. Here's the approach I took: 
        my ($value1, $value2);
foreach (sort keys %hash)
{
  foreach (sort keys %{$hash{$random_name}})
  {
     foreach $k1 (sort keys %{$hash{$random_name}{$fixed_name1}})
     {
        $value1 = $k1;
     }
     foreach $k2 (sort keys %{$hash{$random_name}{$fixed_name2}})
     {
        $value2 = $k2;
     }
etc.
   }
}
print "$value1\n";

        [download]
        Worked a charm. My full version has some error checking in case one of the values didn't exist. Did this with some if defined before the foreach and an else { after.
[reply]
[d/l]
[select]

      Ah. Well, clearly, all the values of the "leaf" nodes in the structure are undef. What you want is the keys of the bottom level of the struct. E.g.: 

      my @values = keys %{ $hash{'test1'}{'fixed name'} };

      [download]
      A word spoken in Mind will reach its own level, in the objective world, by its own weight
[reply]
[d/l]
        But is it possible to have a scalar for each "fixed_name" assigned the value of "value"? I suppose a better representation of the hash would be: 
        $VAR1 = 'random_name                         ';
$VAR2 = {
          'Fixed_name1     ' => {
                            'value    ' => undef
                          },
          'Fixed_name2   ' => {
                            'value    ' => undef
                          }
        };
$VAR3 = 'random_Name                                    ';
$VAR4 = {
          'Fixed_name1       ' => {
                            'value    ' => undef
                          },
          'Fixed_name2   ' => {
                            'value    ' => undef
                          }
        };

        [download]
        The fixed names are always going to be the same but there will be hundreds of random names. I want to return the value of the fixed name to another function that will display this value on a webpage for each random name. There will only ever be 1 element for value. I hope I'm explaining this better each time and not just making it twice as confusing :-)
[reply]
[d/l]

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