Re^2: Regular Expression: search two times for the same number of any signs (updated)

Hi Hauke,

I am trying to fully understand all the new things. One question to your construct "for"

print "$_ =>\n" 
  for qw/ 1 12 123/;
[download]

is working fine. I like this style. But I can not combine it with an if or multiple lines.

{print "$_ =>\n" if $_=/1/ }
  for qw/ 1 12 123/;
[download]

gives me floowing error message: "Missing $ on loop variable at ./test3.pl line 2." and I can not understand, what is mean by this error meassage.

Comment on Re^2: Regular Expression: search two times for the same number of any signs (updated) Select or Download Code

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Re^3: Regular Expression: search two times for the same number of any signs (updated) by haukex (Archbishop) on Nov 29, 2016 at 13:19 UTC
Hi Anonymous, You can't use more than one statement modifier like `for` or `if` at a time (and I think that if you were able to, it would lead to more hard-to-understand code). If your code gets more complex you should instead use a normal `for` loop: `for my $n (qw/1 12 123 234/) { print "$n =>\n" if $n=~/1/; }` [download] (Ok, there is a way to do what you want, but legibility begins to suffer if it gets longer: `/1/ and print "$_ =>\n" for qw/1 12 123 234/;`) Update: I should add that I was golfing a little bit in my example code, and that compressed style is not necessarily something one should strive to use in production code ;-) Regarding the other question about `(??{ })`, that's documented along with `(?{ })` in perlre. The oversimplified explanation is that the code inside `(??{...})` is evaluated and its return value embedded as part of the regular expression (but make sure to read the docs). So in my regex, the code `'.{'.length($2).'}'` takes the length of the string matched in between the first set of x's (`x(.)x`), and then generates an expression like `.{N}` (where N is the length), so if the input were `x12345x67890x`, the regular expression it is matched against is `x.x.{5}x`. Hope this helps, -- Hauke D Updated wordings a little bit.	[reply] [d/l] [select]
Re^4: Regular Expression: search two times for the same number of any signs (updated) by Anonymous Monk on Nov 29, 2016 at 14:33 UTC
Hi Hauke, Many many thanks for your explainations and tips !!!!! Took a while to understand, read and try out ... I really learned thinks , that are a complet new level of perl for me ! Thanks	[reply]