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Re^2: counting overlapping patterns

by Limbic~Region (Chancellor)
on Feb 19, 2005 at 16:14 UTC ( #432743=note: print w/replies, xml ) Need Help??


in reply to Re: counting overlapping patterns
in thread counting overlapping patterns

While discussing other methods that avoided regular expressions in the CB with bobf and nothingmuch, I mentioned an unpack/hash solution. nothinmuch asked to see it, so here is a highly untested alternative.
#!/usr/bin/perl use strict; use warnings; print str_count('ABAABAAAA', 'AA'), "\n"; sub str_count { my ($str, $pat) = @_; my %substr; my ($p_len, $s_len) = (length $pat, length $str); my $template = ("A$p_len" . 'X' . ($p_len - 1)) x ($s_len - $p_len + + 1); $substr{$_}++ for unpack $template, $str; return $substr{$pat}; }

Cheers - L~R

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