"Pandey Rajeev-A19514" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Hi ,
Hello
>
> I need some help me to extract a pattern. The delimiters is a pair of
"abcd" and "efgh". Can some one help me with an efficient use of Greedy and
non greedy matches, look ahead and lookbehind features.
>
> I want the smallest match involving the two delimiters. I want all the
matches. i.e. fisrt match , last match and all ther other matches in
between.
>
Why do this with a regex? Just because it's written in perl doesn't mean you
_have_ to program in regexes.
How about the following solution, finding the delimiters and printing all
the combos?
#/perl -w
my $string = " abcd 1 edfg 2 abcd edfg 3 4 5 abcd 6 7 edfg 8 9";
my $start_delim = 'abcd';
my $end_delim = 'edfg';
my @start_indices;
my @end_indices;
my $current_index = 0;
while ( ($current_index = index($string, $start_delim, $current_index + 1))
ne -1) { push @start_indices , $current_index};
$current_index = 0;
while ( ($current_index = index($string, $end_delim, $current_index + 1))
ne -1) { push @end_indices , $current_index};
foreach my $start (@start_indices) {
foreach my $end (@end_indices) {
next if ($start > $end);
print "$start, $end\n";
}
}
>
> Here is what I tried to extract the first match and the results(a bad one)
I got.
>
> $abc = <<END;
> aaaaaaaaaa
> abcd aaaaa
> abcd bbbbb
> AAAAAAAAAAAAAAA
> BBBBBBBBBBBBBBB
> efgh ccccc
> CCCCCCCCCCCCCCC
> efgh ddddd
> DDDDDDDDDDDDDDD
> EEEEEEEEEEEEEEE
> FFFFFFFFFFFFFFF
> abcd eeeee
> abcd fffff
> GGGGGGGGGGGGGGG
> HHHHHHHHHHHHHHH
> IIIIIIIIIIIIIII
> efgh ggggg
> efgh hhhhh
> JJJJJJJJJJJJJJJ
> KKKKKKKKKKKKKKK
> END
>
> $match = 'abcd(?:(?!abcd).)*efgh.*?\n';
> ($found) = ($abc =~ /($match)(?!$match)/sxi);
> print "*************\nFOUND FIRST MATCH\n$found\n";
>
> The OUTPUT IS :
> *************
> FOUND FIRST MATCH
> abcd bbbbb
> AAAAAAAAAAAAAAA
> BBBBBBBBBBBBBBB
> efgh ccccc
> CCCCCCCCCCCCCCC
> efgh ddddd
>
>
> WHEREAS I wanted it to be
> *************
> FOUND FIRST MATCH
> abcd bbbbb
> AAAAAAAAAAAAAAA
> BBBBBBBBBBBBBBB
> efgh ccccc
>
>
> Any suggestion is welcome.
>
> Thanks in advance.
> Rajeev
>
>
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