Merging Hashes in Perl

Sunday, February 21. 2010

If you want to merge 2 hashes in Perl, you can of course do it manually, e.g. like this:

  %a = ('foo'=>123, 'bar'=>456);

  %b = ('baz'=>789, 'zak'=>100);

  while ( ($k,$v) = each(%a) ) { $c{$k} = $v; }

  while ( ($k,$v) = each(%b) ) { $c{$k} = $v; }

or, a little more elegant:

  [...]

  %c = ( %a, %b );

(see the Perl Cookbook, Chapter 5)

This method of course fails for more complicated situations, e.g.

  %a = (

    names => [ 'Huey', 'Dewey', 'Louie' ],

    age => [12, 13, 14]

  );

  %b = (

    names => [ 'Donald' ],

    age => [96]

  );

Luckily, there's a useful little Perl module on CPAN to handle this:
Hash::Merge

Using it is quite simple:
%c = %{ merge( %a, %b ) };

Posted by Martin Schuster in Coding at 09:08 | Comments (0) | Trackbacks (0)

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