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I'm quite new to regular expressions. Could you help me to create a pattern, which matches whole words, containing specific part? For example, if I have a text string "Perform a regular expression match" and if I search for express, it shuld give me expression, if I search for form, it should give me Perform and so on. Got the idea?

tintix
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2 Answers2

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preg_match('/\b(express\w+)\b/', $string, $matches); // matches expression
preg_match('/\b(\w*form\w*)\b/', $string, $matches); // matches perform,
                                                     // formation, unformatted

Where:

  • \b is a word boundary
  • \w+ is one or more "word" character*
  • \w* is zero or more "word" characters

See the manual on escape sequences for PCRE.

* Note: although not really a "word character", the underscore _ is also included int the character class \w.

Linus Kleen
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  • That is great. Just what i was looking for... +1 – OrPaz Mar 14 '12 at 13:50
  • \b Word boundary, nice... Why haven't I seen that until now? Useful. – Andrew Dec 17 '15 at 20:38
  • beware because "+" is considered as a word boundary in PHP regex ! – Nadir Oct 03 '18 at 09:56
  • @Nadir Care to elaborate? Within a regular expression `+` is _"one or more characters"_. Outside, really anything that's not `[a-z]` is considered a word boundary. But why should I beware? I don't get the context. – Linus Kleen Oct 04 '18 at 07:38
  • here are more details: I had this issue is with the following code: preg_match_all("/#(\\w+)/", "#a2+u2lis", $hashtags); - I needed to workaround the fact that \w considers "+" as a word boundary : you end up with 2 words while I just want "a2+u2lis" in the result (context: it is PHP 5.3) – Nadir Oct 05 '18 at 09:30
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This matches 'Perform':

\b(\w*form\w*)\b

This matches 'expression':

\b(\w*express\w*)\b
Kyle Wild
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