similar to some of the above requests, but how about a quick and easy: 
print number_of_uniques('ppppppperlguy') . "\n";

sub number_of_uniques {
   my %s;
   return scalar (grep !$s{$_}++, split '', $_[0]);
}

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In reply to Re: number of unique characters in a string by perlguy
in thread number of unique characters in a string by Anonymous Monk

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