正则表达式 - 为什么不。*（点星）匹配换行符？

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?

Answer 1

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.

Answer 2

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.

Answer 3

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 ).