Regex dilemma

[AO940]

I've read regex tutorials but still have not found the answer to this question.

How do you do a prel-style negation so that a search result is omitted if a specified pattern of characters (string) is found *anywhere* in a list of words? Example: Find exp1 but skip if exp2 is also found in the same string.

[KEYWORDS:]
exp1something /*found, exp1 found, but not exp2
exp1somethingexp2 /*skipped, exp1 found but exp2 also found
someexp1thing /*found
somethingexp1 /*found
exp2exp1 /skipped, because the string exp2 was found

Could it be just (!exp2)

 

[TrojanWarBlade]

Sounds like you need two regexs to me.

Trojan.

 

[rharsh]

You could do it with a negative look-behind and look-ahead, but why?

I agree with Trojan, it makes better sense to use two regexs.

 

[brigmar]

my @strings=('exp1something','exp1somethingexp2','someexp1thing','somethingexp1','exp2exp1');

for (@strings) {
  print "$_\n" if !/exp2/ and /exp1/;
}

Due to the 'and' operator shortcutting, /exp1/ won't even be evaluated unless it can't find exp2.

Trojan's on the money, as usual. Using two regexes 'reads' better and makes sense when you come to look at it later.

 

[AO940]

Thanx for the info. But as far as I know, strings appear in parentheses. So, instead of writing !/exp2/, is it also possible to write the same expression as !(exp2)?

 

[ishnid]

Simple answer: no.

!(exp2)? looks for a literal exclamation mark followed by the optional string `exp2'. brigmar's solution is what you need. Doing all this in a single regexp will be an unmaintainable nightmare, even if you managed to write one.