You must remember that (?=...) is a zero-width assertion. Thus (\d{3})(?=(\d{3})+)$ tries to first match three digits, then sees if the text after where it is in the string matches (\d{3})+ without moving further in the string and then sees it can match an end of string or newline after its current location in the string.

In reply to Re: bug in regexp engine? by wog
in thread bug in regexp engine? by stefp

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