in reply to Help with matching .org

Essentially you are searching for something that is delimited either by whitespaces or by end of string/line, right?

In this case your regexp should look something like this: 

# custom word boundary:
my $wb = qr{ ^ | $ | \s }x;

# you have to take care if you are checking for a left or a right word
+ boundary:
if ($str =~ m/(?<=$wb)$termstr1(?=$wb)/){
   ...
}

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Re^2: Help with matching .org
by bestresearch2 (Novice) on Jan 09, 2008 at 15:11 UTC
    Thanks! Delimited by whitespace, end of string/line, or beginning of string/line. Will this work for that too?
[reply]
      hmmm. Perl does not like variable length lookaround. But it seems I can get away with (the less efficient): 
      m/(^|?|\s)string(^|?|\s)/

      [download]
      Thanks for your help!!!
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[d/l]
        Perl does not like variable length lookaround.

        It doesn't like variable length look-behinds but variable length look-aheads are ok. You can get around the limitation by specifying an alternation of different length look-behinds, for example

        if ( $str =~ m{ (?: (?<=\A) | (?<=XXX) ) \d+ }x ) { ... }

        [download]

        i.e do something if we find one or more digits preceded by either the beginning of the string or three 'X's. Note that I use the 'x' pattern modifier to allow whitespace and comments inside the pattern to aid readability.

        I hope this is of use.

        Cheers,

        JohnGG

[reply]
[d/l]

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