in reply to Regex (counting) confusion :(

The 2 comes from the fact that "x*" can match nothing. For "xxxx", "x*" matches the null width "beginning" then matches all the "x"s to the end. The 9 is because of the non-greediness, so you get a match at the null-width beginning, at each character, between each character, and the end.
UPDATE: I ran your original code using "use re 'debug'" and it looks like when you get 2 it is actually matching the "xxxx" and then the end not the beginning.

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Re: Regex (counting) confusion :(
by Abigail-II (Bishop) on Sep 18, 2003 at 14:40 UTC
    For "xxxx", "x*" matches the null width "beginning" then matches all the "x"s to the end.

    Well, that would mean the first result would be 1, not 2. What happens is that /x*/ matches the zero-length string at the beginning, all the x-es, but not the zero-length string at the end. After the first substitution, the regex hasn't reached the end of the string yet, so /g kicks in. All that's left is the zero-width string at the end - this is now matched (were it wasn't before), and hence we get a second substitution, resulting in a result of 2 and a final "##" string.

    Frankly, I find this behaviour unexpected and unwanted. I'd call it a bug, but I bet someone once had a use for this, and now that's the way it goes.

    Abigail

[reply]
      That's what I was looking for. Danke schoen!
[reply]

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