Re^4: how to find particular string and store in to variable

Interestingly, what is captured to $var in a statement like

my ($var) = $s =~ m{ (\d+) \z }xms;
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is not the same as what is captured to $1:

Isn't that just because the RE didn't match the first time through the loop, so $1 still held 'zot' ?

If your RE did match the first time through, $1 would have been reset and would therefore match $var ...

Comment on Re^4: how to find particular string and store in to variable Download Code

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Re^5: how to find particular string and store in to variable by AnomalousMonk (Archbishop) on Jun 25, 2015 at 14:39 UTC
Isn't that just because the RE didn't match the first time through the loop ... Yes, and I've clarified the language used above a bit. But I still find the difference interesting: a potential pitfall. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l]
Re^6: how to find particular string and store in to variable by 1nickt (Canon) on Jun 25, 2015 at 16:08 UTC
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!	[reply] [d/l] [select]