Match string that doesn't contain a specific word

Question

I'm working with ruby with the match method and I want to match an URL that doesn't contain a certain string with a regular Expression: ex:

http://website1.com/url_with_some_words.html
http://website2.com/url_with_some_other_words.html
http://website3.com/url_with_the_word_dog.html

I want to match the URLs that doesn't contain the word dog, so the 1st and the 2nd ones should be matched

This question is best answered on posting [here](http://stackoverflow.com/questions/406230/regular-expression-to-match-string-not-containing-a-word) Searching SO for similar questions is a good idea. — Vaman Kulkarni, Jul 25 '12 at 16:28

score 52 · Accepted Answer · answered Jul 22 '13 at 21:06

52

Just use a negative lookahead ^(?!.*dog).*$.

Explanation

^ : match begin of line
(?!.*dog) : negative lookahead, check if the word dog doesn't exist
.* : match everything (except newlines in this case)
$ : match end of line

Online demo

answered Jul 22 '13 at 21:06

HamZa

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Wow, this piece of info was surprisingly difficult to find. – B Seven Oct 26 '15 at 22:07

score 9 · Answer 2 · edited Nov 28 '14 at 19:11

9

Just use

string !~ /dog/

to select strings you need.

edited Nov 28 '14 at 19:11

nicholaides

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answered Jul 25 '12 at 16:06

Anton

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score 2 · Answer 3 · answered Jan 05 '14 at 13:26

2

There's actually an incredibly simple way to do this, using select.

array_of_urls.select { |url| !url.match(/dog/) }

this will return an array of the url's that don't contain the word 'dog' anywhere in it.

answered Jan 05 '14 at 13:26

nfriend21

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More succinctly, `array_of_urls.reject { |url| url.match(/dog/) }` – nicholaides Nov 28 '14 at 19:12

score 0 · Answer 4 · answered Feb 11 '16 at 16:03

Another thing you can use is:

!url['dog']

With your example:

array = []
array << 'http://website1.com/url_with_some_words.html'
array << 'http://website2.com/url_with_some_other_words.html'
array << 'http://website3.com/url_with_the_word_dog.html'

array.select { |url| !url['dog'] }

You could also reject the urls that do contain 'dog':

array.reject { |url| url['dog'] }

Match string that doesn't contain a specific word

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