comparing keys and values in different hashes

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

Hi monks, I basically want to compare the keys between two hashes to see which they have in common. If they have one in common I want to multiply the values of both keys together. I have managed to do the comparing part, but not sure how to multiply the values. Please can anyone help?? e.g. Ideal output;

dog = 55
cat = 12
[download]

The code;


my %hash = (

     'dog' => '5',
     'sheep' => '10',
     'cat' => '3',

  );

my %hash2 = (

      'dog' => '11',
      'budgie' => '1', 
      'cat' => '4',

  ); 

foreach (keys %hash2)    {


     if (exists $hash{$_})   {

       print "$_ exists";
  
    }

}
[download]

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Re: comparing keys and values in different hashes by fruiture (Curate) on Mar 03, 2003 at 14:04 UTC
You're very close: `foreach( keys %hash2 ){ if( exists $hash1{$_} ){ print "$_ = ",$hash2{$_}*$hash1{$_},"\n"; } }` [download] btw.: please don't quote numbers (like '5') if you want them to be numbers and not strings: It's both confusing and (although only in microseconds) slows perl down. `my %hash = ( dog => 11, budgie => 1, #... )` [download] -- http://fruiture.de	[reply] [d/l] [select]
Re: comparing keys and values in different hashes by broquaint (Abbot) on Mar 03, 2003 at 14:06 UTC
`my %hash = ( dog => 5, sheep => 10, cat => 3, ); my %hash2 = ( dog => 11, budgie => 1, cat => 4, ); print "$_: ", $hash{$_} * $hash2{$_}, "\n" for grep exists $hash2{$_}, keys %hash; __output__ cat = 12 dog = 55` [download] Be careful not to stringify your numeric values or you could get unexpected results. HTH `_________ broquaint`	[reply] [d/l]
Re: comparing keys and values in different hashes by robartes (Priest) on Mar 03, 2003 at 14:04 UTC
Have a look at perldata for the syntax to access hash values. CU Robartes-	[reply]
Re: comparing keys and values in different hashes by Russ (Deacon) on Mar 03, 2003 at 18:46 UTC
This post may be interesting to you, in comparing two hashes. Synopsis: `my %Diffs = ((map(($_ => [$R{$_}, undef]), grep {not exists $S{$_}} k +eys %R)), (map(($_ => [undef, $S{$_}]), grep {not exists $R{$_}} k +eys %S)), (map(($_ => [$R{$_}, $S{$_}]), grep {exists $S{$_} and $R +{$_} ne $S{$_}} keys %R)));` [download] Russ	[reply] [d/l]