preg_replace_callback 的意外行为

Question

我认为 php 的 preg_replace_callback 函数存在运行时问题：

$a = [
        'test.db',
        'WhatsApp Image 2021-10-21 at 18.52.14.jpeg',
        'WhatsApp Image 2021-10-21 at 18.52.15.jpeg',
        'WhatsApp Image 2021-10-21 at 18.52.16.jpeg',
        'WhatsApp Image 2021-10-21 at 18.52.18 (1).jpeg',
        
       ];
    
     $callback = function ($matches) {
            return $matches[0];
        };
        
    $c = preg_replace_callback('/.*\.[jp][pn]e?g/i', $callback, $a );
        
    print_r($c);

return :

Array
(
    [0] => test.db
    [1] => WhatsApp Image 2021-10-21 at 18.52.14.jpeg
    [2] => WhatsApp Image 2021-10-21 at 18.52.15.jpeg
    [3] => WhatsApp Image 2021-10-21 at 18.52.16.jpeg
    [4] => WhatsApp Image 2021-10-21 at 18.52.18 (1).jpeg
)

为什么 test.db 仍然存在，即使当我解析 return $matches[0] 它永远不适合里面？

Answer 1

preg_replace_callback 对数组中的每一项进行替换，但如果没有可替换的内容，它仍然 returns 元素不变。

preg_filter就是你所需要的。

preg_filter() is identical to preg_replace() except it only returns the (possibly transformed) subjects where there was a match.

旁注：/.*\.[jp][pn]e?g/i 将匹配 foo.jpg.exe。您可能需要 /.*\.[jp][pn]e?g$/i。

preg_replace_callback 的意外行为

Unexpected behavior of preg_replace_callback

php