How can I match a string that is NOT partners?
Here is what I have that matches partners:
/^partners$/i
I've tried the following to NOT match partners but doesn't seem to work:
/^(?!partners)$/i
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2I don't know. But can't you just invert the result returned by whatever regex function you're using?Oliver Charlesworth– Oliver Charlesworth2011-12-28 22:06:18 +00:00Commented Dec 28, 2011 at 22:06
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In what programming language?Óscar López– Óscar López2011-12-28 22:09:13 +00:00Commented Dec 28, 2011 at 22:09
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4 Answers
Your regex
/^(?!partners)$/i
only matches empty lines because you didn't include the end-of-line anchor in your lookahead assertion. Lookaheads do just that - they "look ahead" without actually matching any characters, so only lines that match the regex ^$ will succeed.
This would work:
/^(?!partners$)/i
This reports a match with any string (or, since we're in Ruby here, any line in a multi-line string) that's different from partners. Note that it only matches the empty string at the start of the line. Which is enough for validation purposes, but the match result will be "" (instead of nil which you'd get if the match failed entirely).
Comments
not easily but with the look ahead operator it can. Here the ruby regex
^((?!partners).)*$
Cheers
1 Comment
Tim Pietzcker
This matches any string that doesn't contain
partners, which is possibly not what Jacob wanted. At least it's not what he asked for.If you only want to get a true value when string is not partners then there is no need to use regex and you can just use a string comparison (which ignores case).
If you for some reason need a positive regex match for any string which does not contain partners (if it's a part of a larger regex for example) you could use several different constructs, like:
`^(?:(?!partners).)*$`
or
^(?:[^p]+|p(?!artners))*$
Comments
For example, in Java:
!"partners".equalsIgnoreCase(aString)
