[IMG]标签之间的预匹配内容

Question

I'm writing a script that retrieves the first image link in a post

$content = [center]Hello World, this is my house: [img]myhouse.png[/img] blah blah blah blah [/center] This is another house [img]anotherhouse.png[/img] , blah blah blah

I would like to just return "myhouse.png" and save it into a variable Also img should be case insensitive, meaning it would work on [img]text-here[/img] or [IMG]text-here[/IMG]

Answer 1

This will return the first image:

$content = '[center]Hello World, this is my house: [img]myhouse.png[/img] blah blah blah blah [/center] This is another house [img]anotherhouse.png[/img] , blah blah blah';

preg_match('#\[img\]\s*(?P<png>.*?)\s*\[/img\]#i', $content, $m);
echo $m['png']; // myhouse.png

Answer 2

Here comes a regex:

$content = '[center]Hello World, this is my house: [img]myhouse.png[/img] blah blah blah blah [/center] This is another house [img]anotherhouse.png[/img] , blah blah blah';

$pattern = '/\[img\](.*)\[\/img\]/U'; // <-- the U means ungreedy

preg_match_all($pattern, $content, $matches);
var_dump($matches[1]);

Explanation:

The regex matches everything between a pair of [img] ... [/img] tags. To make sure that it will not match all text between the first [img] and the last [/img] tag I've use the ungreedy modifier.

Learn more about PHP's regex syntax.