Not sure of this since I'm a little unclear how $regexp was generated. How ever, you may want to look into the function index.

Update: Hmm. index looks to be blank.

index STR, SUBSTR, OFFSET
This function searches for one string within another. It returns the position of the first occurance of SUBSTR in STR. The OFFSET, if specified, says how many characters from the start to skip before beginning to look.
Returns -1, if not found, positions based of off 0, and there's also rindex.

Most of that quoted from the Camel

In reply to Re: Getting information about regexp matches by lemming
in thread Getting information about regexp matches by ariels

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