问题
I've been using the following site to test a PHP regex so I don't have to constantly upload: http://www.spaweditor.com/scripts/regex/index.php
I'm using the following regex:
/(.*?)\.{3}/
on the following string (replacing with nothing):
Non-important data...important data...more important data
and preg_replace is returning:
more important data
yet I expect it to return:
important data...more important data
I thought the ? is the non-greedy modifier. What's going on here?
回答1:
Your non-greedy modifier is working as expected. But preg_match replaces all occurences of the the (non-greedy) match with the replacement text ("" in your case). If you want only the first one replaced, you could pass 1 as the optional 4th argument (limit) to preg_replace function (PHP docs for preg_replace). On the website you linked, this can be accomplished by typing 1 into the text input between the word "Flags" and the word "limit".
回答2:
just an actual example of @Asaph solution. In this example ou don't need non-greediness because you can specify a count. replace just the first occurrence of @ in a line with a marker
$line=preg_replace('/@/','zzzzxxxzzz',$line,1);
来源：https://stackoverflow.com/questions/1899158/php-preg-replace-non-greedy-trouble