添加一個字符串之前削減

Question

後，如果我有以下URL作爲一個字符串：

www.example.com/img/1.png 

我怎麼會添加字符串extra/在URL中的最後一個斜槓之後，那麼其結果是：

www.example.com/img/extra/1.png 

Answer 1

使用preg_replace()：

echo preg_replace('#(/[^/]+)(?=/[^/]+/?$)#', '$1/extra', $url); 

說明：

(  # group and capture to backreference $1 
/ # match literal '/' 
    [^/]+ # any character except: '/' (1 or more times) 
)  # end of capturing group 1 
(?=  # look ahead to see if there is: '/' 
    [^/]+ # any character except: '/' (1 or more times) 
    /?  # '/' (optional) 
    $  # assert position at the end of string 
)  # end of look-ahead 

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