Re^3: how to find particular string and store in to variable

But I was matching against (\d*) \z which cannot fail, although it could match an empty string of digits — which can be useful in and of itself!

Update: Interestingly, what is ~~captured~~ | assigned to $var in a statement like
my ($var) = $s =~ m{ (\d+) \z }xms;
is not the same as what is captured to | not necessarily the same as the value of $1:

c:\@Work\Perl\monks>perl -wMstrict -le
"'zot' =~ m{ (zot) }xms;
 ;;
 for my $s (
   'http://172.20.37.115:8080/se/1.0/pro/subs/198968/',
   'http://172.20.37.115.8080/se/1.0/pro/123456',
   ) {
   my ($var) = $s =~ m{ (\d+) \z }xms;
   print '$var is ', defined($var) ? '' : 'UN', 'defined';
   print qq{'$s' -> '$var' (\$1 is '$1')};
   }
"
$var is UNdefined
Use of uninitialized value $var in concatenation (.) or string at -e l
+ine 1.
'http://172.20.37.115:8080/se/1.0/pro/subs/198968/' -> '' ($1 is 'zot'
+)
$var is defined
'http://172.20.37.115.8080/se/1.0/pro/123456' -> '123456' ($1 is '1234
+56')
[download]

This warrants a bit more research!

Give a man a fish: <%-(-(-(-<

Comment on Re^3: how to find particular string and store in to variable Select or Download Code

Replies are listed 'Best First'.
Re^4: how to find particular string and store in to variable by 1nickt (Canon) on Jun 25, 2015 at 14:16 UTC
Interestingly, what is captured to $var in a statement like `my ($var) = $s =~ m{ (\d+) \z }xms;` [download] 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 ...	[reply] [d/l]
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]
Re^4: how to find particular string and store in to variable by 1nickt (Canon) on Jun 25, 2015 at 14:13 UTC
Anomalous, sorry, my comment was not in response to yours, but to the one above it by Stevieb :-)	[reply]
Re^5: how to find particular string and store in to variable by AnomalousMonk (Archbishop) on Jun 25, 2015 at 14:23 UTC
... you'd want that RE within an `if` condition ... to ... Stevieb ... Ah! In that case, it's a very good point! I hadn't noticed it myself. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]