“未知”修饰符“c”在正则表达式中的含义是什么？ [重复]

Question

This question already has an answer here:

• Warning: preg_replace(): Unknown modifier ']' 3 answers

I'm a newbie with regular expressions and i need some help :).

I have this:

$url = '<img src="http://mi.url.com/iconos/oks/milan.gif" alt="Milan">';
$pattern = '/<img src="http:\/\/mi.url.com/iconos/oks/(.*)" alt="(.*)"\>/i';

preg_match_all($pattern, $url, $matches);

print_r($matches);

And I get this error:

Warning: preg_match_all() [function.preg-match-all]: Unknown modifier 'c'

I want to select that 'milan.gif'.

How can I do that?

</div>

Answer 1

If you’re using / as delimiter, you need to escape every occurrence of that character inside the regular expression. You didn’t:

/<img src="http:\/\/mi.url.com/iconos/oks/(.*)" alt="(.*)"\>/i
                              ^

Here the marked / is treated as end delimiter of the regular expression and everything after is is treated as modifier. i is a valid modifier but c isn’t (see your error message).

So:

/<img src="http:\/\/mi\.url\.com\/iconos\/oks\/(.*)" alt="(.*)"\>/i

But as Pekka already noted in the comments, you shouldn’t try to use regular expressions on a non-regular language like HTML. Use an HTML parser instead. Take a look at Best methods to parse HTML.