I've used the next trick several times (update see also barts reply below for some -necessary- additional pointers): 
use strict;                                           
my %temphash = ( "tom" => "good", "dick" => "bad", "hary" => "ugly" );
my $temp = "This is a string containing tom and dick";

my $regexp = join('|',keys %temphash);
print "Found: [$1]\n" while ( $temp =~ /($regexp)/cg );

[download]
Which results in: 
Found: [tom]
Found: [dick]

[download]

-- JaWi

"A chicken is an egg's way of producing more eggs."

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

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