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Posted by PerlFAQ Server on March 4, 2008, 3:03 pm
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This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .
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4.64: How can I get the unique keys from two hashes?
First you extract the keys from the hashes into lists, then solve the
"removing duplicates" problem described above. For example:
%seen = ();
for $element (keys(%foo), keys(%bar)) {
$seen++;
}
@uniq = keys %seen;
Or more succinctly:
@uniq = keys %};
Or if you really want to save space:
%seen = ();
while (defined ($key = each %foo)) {
$seen++;
}
while (defined ($key = each %bar)) {
$seen++;
}
@uniq = keys %seen;
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