Regex - Why doesn't this .* (dot-star) match line-breaks?

Question

/(<pre>|<code>|\[code])(.*)(</pre>|</code>|\[/code])/gi

This works if I have something such as:

<code>foobar</code>

But if I were to have a line-break like this:

<code>
    Awesome
</code>

It will not match it, what am I doing wrong?

score 16 · Accepted Answer · answered Jan 19 '12 at 00:28

16

You do need the DOTALL modifer /s, because the . dot per default excludes linebreaks. The /g modifier OTOH is not legal in PHP and PCRE.

You should also use .*? to not match too wide.

answered Jan 19 '12 at 00:28

mario

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score 6 · Answer 2 · answered Jan 19 '12 at 00:30

6

In PCRE, "." does not match every character, it matches every thing that isn't a newline:

Outside a character class, a dot in the pattern matches any one character in the subject, including a non-printing character, but not (by default) newline.

(http://www.php.net/manual/en/regexp.reference.dot.php)

Try something like [\s\S] instead.

answered Jan 19 '12 at 00:30

Kara Brightwell

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Or, you know, you can listen to any of the three other valid answers that popped up while I was writing mine. – Kara Brightwell Jan 19 '12 at 00:31

score 3 · Answer 3 · answered Jan 19 '12 at 00:29

Because . matches every character except newline by default, unless you feed in the s switch.

See explanation of regex switches here.

In particular

s (PCRE_DOTALL) If this modifier is set, a dot metacharacter in the pattern matches all characters, including newlines. Without it, newlines are excluded.

So /(<pre>|<code>|\[code])(.*)(</pre>|</code>|\[/code])/is.

(No g, use preg_match_all).

Regex - Why doesn't this .* (dot-star) match line-breaks?

3 Answers3