How to use match two cases using regular expression?

Question

Given a sentence,

Scheme is such a bizarre programming language.

So any sentence that contains is and language should return true. I found | means or, but couldn't find any symbol means and.

Thanks,

@tchrist: Thanks. But if I put `islanguage`, how does regex know i mean a whole word, or two separate words? — roxrook, Apr 23 '11 at 05:06
You don't need regular expressions to find such strings (although a regular expression is guaranteed to exist because [regular languages are closed under intersection](http://en.wikipedia.org/wiki/Regular_language#Closure_properties) and the sets of strings that have "is" or "language" as substrings are regular). You could just perform two substring searches. Is it a requirement that "is" appear before "language"? — Josh Rosen, Apr 23 '11 at 05:14
It knows if you say "something and then is and the something and then language and then something", thus more than one and. — Howard, Apr 23 '11 at 05:15

score 3 · Answer 1 · answered Apr 23 '11 at 05:16

3

Try the following regex:

\bis\b.*\blanguage\b

This one will match if the two words appear in exactly that order. \b (word boundary) means that the words are standalone.

answered Apr 23 '11 at 05:16

Howard

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@Chan What language do you use? Try e.g. ".*\bis\b.*\blanguage\b.*" or ".*\\bis\\b.*\\blanguage\\b.*" – Howard Apr 23 '11 at 05:36
I'm using Scheme with DrScheme. – roxrook Apr 23 '11 at 05:51

score 3 · Accepted Answer · edited May 23 '17 at 11:47

3

You can use the idiom.

(?=expr)

For example,

(?=.*word1)(?=.*word2)

For more details, please refer to this threads.

edited May 23 '17 at 11:47

Community

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answered Apr 23 '11 at 05:17

jumperchen

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score 0 · Answer 3 · answered Apr 23 '11 at 05:17

0

Kinda ugly, but it should work (regardless of the how 'is' and 'language' are ordered):

(.*is.*language.*|.*language.*is.*)

answered Apr 23 '11 at 05:17

dmitrii

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The answer from @jumperchen is much better than mine! – dmitrii Apr 23 '11 at 05:21

score 0 · Answer 4 · answered Apr 23 '11 at 05:21

In c# (and I know you didn't ask about c#, but it illustrates how this can be done much quicker)...

 string s = "Scheme is such a bizarre programming language.";
 if ((s.Contains(" is") || s.Contains("is ")) &&  
     (s.Contains(" language") || s.Contains("language ")))
 {
    // found match if you got here
 }

Regexs can be slow and hard to parse by someone who is reading your code. Simple string matches are quicker generally.

EDIT: This doesn't care about the order of the words and works for simple whitespace only

score 0 · Answer 5 · answered Apr 23 '11 at 05:21

0

Try this one if you don't care about the order of the words in the sentence:

\bis\b.*\blanguage\b|\blanguage\b.*\bis\b

answered Apr 23 '11 at 05:21

Wes

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Thanks but I do care about the order. – roxrook Apr 23 '11 at 05:28

How to use match two cases using regular expression?

5 Answers5