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

[moritz]

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

If you really want a regex-solution (which isn't necessarily the best idea), here's one from the bottom of the poison cabinet:

use strict;
use warnings;
use 5.010;

$_ = '79899920179';

my $pass = qr/(?=)/;
my $fail = qr/(*FAIL)/;
while (/\G(\d{2,}?)(??{ $1 >= 32 ? $pass : $fail  })/g) {
    say $1;

}

I'm sure that can be simplified somehow, but right now I don't know how.

Be sure to read the warning about (??{...}) in perlre.

And here's a nicer Perl 6 solution:

$ perl6 -e 'say "79899920179".comb(/ (\d **? 2..*) <?{ $0 >= 32 }>/)'
79 89 99 201 79

[AnomalousMonk]

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'

[venky4289]

Hi this works perfectly fine. Can you explain me the regulsr expression as i am nee to perl programming

[AnomalousMonk]

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.