PHP Regexp negative lookahead

问题

I'm trying match all words wrapped with { } but not the words with "_loop". I can't see where I'm going wrong with my reg expression.

 $content   = '<h1>{prim_practice_name}</h1><p>{prim_content}</p><p>Our Locations Are {location_loop}{name} - {state}<br/>{/location_loop}</p>';
 $pattern = '/\{(\w*(?!\_loop))\}/';

回答1:

This happens because \w* "eats" the stopping word "_loop" before your check, to prevent that you should check the word first (before \w*), like the following:

$pattern = '/\{((?!\w*_loop\})\w*)\}/';

or you can use: ?< ! :

$pattern = '/\{(\w*(?<!_loop))\}/';

来源：https://stackoverflow.com/questions/15626955/php-regexp-negative-lookahead