Re^2: how to split the string into two or three numbers based on certain value.

in reply to Re: how to split the string into two or three numbers based on certain value.
in thread how to split the string into two or three numbers based on certain value.

A slight simplification. I'm not sure the \G is necessary: the given test string produces the same groups with/without it. (Update: And the same caveat about a regex solution possibly not being optimum.) See Extended Patterns in perlre.

>perl -wMstrict -le
"my $s = '79899920179';
 ;;
 my @n = $s =~ m{ \G (\d{2,3}?) (?(?{ $^N < 32 }) (*FAIL)) }xmsg;
 printf qq{'$_' } for @n;
"
'79' '89' '99' '201' '79'
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Re^3: how to split the string into two or three numbers based on certain value. by venky4289 (Novice) on Feb 12, 2013 at 08:19 UTC
Hi this works perfectly fine. Can you explain me the regulsr expression as i am nee to perl programming	[reply]
Re^4: how to split the string into two or three numbers based on certain value. by AnomalousMonk (Archbishop) on Feb 12, 2013 at 15:41 UTC
Can you explain me the regulsr expression ... I can begin to explain it and then pass you off to some explanations in the docs that do a better job than I could. `\G` Begin a 'global' search (i.e., a search controlled by the `/g` regex modifier) at the exact position where the previous search left off, or at the start of the string (same as `\A`) if there was no previous search. `(\d{2,3}?)` Capture two or three decimal digits. Because the `?` 'lazy' match modifier controls matching, try first to capture two digits (normal matching would be 'greedy' and try to grab three). `(?(?{ $^N < 32 }) (FAIL))` If the two digits captured by the immediately previous capture group (see `$^N` in perlvar) are numerically less than 32, fail that match and go back and try for three digits. Here's where I bail out. See Extended Patterns in perlre and search for the `"(?(condition)yes-pattern)"` discussion; also check the Conditional expressions section in perlretut. Check Special Backtracking Control Verbs in perlre for info on `(FAIL)`; see also the Backtracking control verbs discussion in perlretut. (Note that `(*FAIL)` can be replaced by `(?!)` if you're scared by the "WARNING: These patterns are experimental and subject to change..." language prefacing documentation of these verbs.) HTH.	[reply] [d/l] [select]

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