SPUG: Counting the number of instances in a string using Perl's regexes...

[Daniel Chetlin]

On Mon, Dec 18, 2000 at 11:51:43AM -0800, Jonathan Gardner wrote:
> Say I had a string with a whole bunch of characters - "asdfjkhafjklhaf".
> 
> How would I go about counting the number of individual characters (say,
> 'a')?

Quickest and most idiomatic for counting a single character:

$string = "asdfjkhafjklhaf";            # => asdfjkhafjklhaf
$count = $string =~ tr/a//;             # => 3
$string;                                # => asdfjkhafjklhaf

(In other words, don't be afraid of tr/// -- it doesn't always modify
the string it operates on).

Most idiomatic for more than a single character:

$count = () = $string =~ /af/g;         # => 2

-dlc

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