Another method not involving regular expressions -- well, okay, ignoring the one in split -- is the following:
use strict;
my %temphash = ("tom" => "good", "dick" => "bad", "hary" => "ugly");
my $string = 'This string contains tom and dick';
my @occurrences = grep {exists $temphash{$_}} split(/\s/, $string);
print scalar @occurrences;

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If you want to know where the matches occur, you can use map instead of grep.

Is this faster than the regexp method? I'm not sure. The hash lookups are certainly quick enough...

In reply to Re: how to find hash keys in a string ? by Dr. Mu
in thread how to find hash keys in a string ? by Anonymous Monk

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