Anomalous, yes, it is a definite potential pitfall, one into which I have fallen myself. But like many a Perl pitfall, one you are likely to avoid thereafter!

I can't remember how it was I screwed myself, but I do remember that I started to test whether a RE matched before using a backreference EVERY time thereafter!

Typically obtuse tchrist documentation in perlre provided the "cluebat" when I eventually found it:

The numbered match variables ($1, $2, $3, etc.) and the related punctuation set ($+ , $& , $` , $' , and $^N ) are all dynamically scoped until the end of the enclosing block or until the next successful match, whichever comes first. (See Compound Statements in perlsyn.)

NOTE: failed matches in Perl do not reset the match variables, which makes it easier to write code that tests for a series of more specific cases and remembers the best match.

(emphasis added)

So yeah, it's interesting, but documented. Not that that keeps me out of every pitfall I encounter!

In reply to Re^6: how to find particular string and store in to variable by 1nickt
in thread how to find particular string and store in to variable by bhushanQA

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