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in reply to counting overlapping patterns

The key is to match without consuming text. The following works. 
while("AAAA" =~ /(?=AA)/g){
  $count++;
}

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It'll go through it repeatedly, starting at each position, but never consuming anything.

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Re^2: counting overlapping patterns
by ikegami (Patriarch) on Feb 18, 2005 at 21:46 UTC

    Alternatively,

    while ('AAAA' =~ /A(?=A)/g) {
   $count++;
}

    [download]

    which looks slightly less weird to me.

[reply]
[d/l]
      But requires rewriting the pattern. Mine will work even if the pattern comes from a variable, or contains different possibilities for the first character ('/AA|BB/' becomes '/(?=AA|BB)/'). My approach was to try to do minimal tinkering with the original, but yeah, it's not as obvious what's actually going on.
[reply]
[d/l]
[select]
        Good point.
[reply]

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