的preg_replace第一匹配模式包括削減

Question

如何去除第一圖案匹配時字符串內容「/」

$a = "abc/def"; 
$b = "abc/def/ghi/abc/def"; 

$result = "/ghi/abc/def"; when replace with "abc/def" only look for the fist match 


I try this but is not work. 
$x = preg_replace('/'.$a.'/', '', $b, 1); 

Answer 1

你必須記住，preg_replace函數的第一個參數是一個正則表達式，所以你不能傳遞只是任何字符串。

首先你需要逃避所有的正則表達式字符功能preg_quote

嘗試：

$a = "abc/def"; 
$b = "abc/def/ghi/abc/def"; 

$pattern = preg_quote($a, '/'); // second argument allows us to escape delimiter chars, too 

$x = preg_replace("/$pattern/", '', $b, 1);