用preg replace php只替换最后一个匹配的字符串

Question

I have this string :

use A\B\C;
use A\B\C;

var $foo;
/*
* comment
*/

use D\E\F;

Class Foo {

How i can replace the last string that beginning with use. In example above must be "use D\\E\\F;" as the result.

I have found many ways but no luck. including with lookahead negative (?!) but was confused how to use it. So this the i can get now " use(.*); " but this was replaced all the matched string.

Thanks.

Answer 1

You can use this regex with s switch (DOTALL) for search:

'/use [^\n]*(?!.*?use)/s'

Online Demo: http://regex101.com/r/dX9hQ9

Code:

$re = '/use [^\n]*(?!.*?use)/s'; 
$str = 'use A\B\C;
use A\B\C;
var $foo;
/*
* comment
*/
use D\E\F;
Class Foo {'; 

preg_match($re, $str, $matches);

Explanation:

• s modifier makes dot match new lines
• use [^\\n]* matches text use untile new line is found
• (?!.*?use) is a Negative Lookahead which matches previous regex only if it is not followed by another use