PHP的问题：如何array_intersect_assoc（）递归 [英] PHP Question: how to array_intersect_assoc() recursively

问题描述

比方说，我想这样做：

$a = array_intersect_assoc(
 array(
  'key1' => array(
   'key2' => 'value2'
  ),
  'key3' => 'value3',
  'key4' => 'value4'
 ),

 array(
  'key1' => array(
   'key2' => 'some value not in the first parameter'
  ),
  'key3' => 'another value'
 )
);

var_dump( $a );

打印的结果是：

array
  'key1' => 
    array
      'key2' => string 'value2' (length=6)

很显然，与KEY2在两个数组关联的值是不一样的，但 array_intersect_assoc（）还是回到键2'=> '值'作为相交的值。

It's clear that values associated with 'key2' in both arrays are not the same, however array_intersect_assoc() still return 'key2' => 'value2' as the intersected value.

这是的预期的行为array_intersect_assoc（）？

谢谢！

推荐答案

是的，这是预期的行为，因为比较字符串使用重新presentations完成，并且该功能不下来递归嵌套的数组。从手动：

Yes, it's the expected behavior, because the comparison is done using string representations, and the function does not recurse down nested arrays. From the manual:

在键=>值，这两个值的对被认为是平等的前提的（字符串）$ elem1 ===（字符串）$ elem2时的。换句话说严格类型检查被执行，以便该字符串重新presentation必须相同。

The two values from the key => value pairs are considered equal only if (string) $elem1 === (string) $elem2 . In other words a strict type check is executed so the string representation must be the same.

如果你试图用'键1'=＆GT数组相交; 数组，你会得到相同的结果，因为数组的字符串重新presentation总是数组。

If you tried to intersect with an array with 'key1' => 'Array', you'd get the same result because the string representation of an array is always 'Array'.

一位用户注释的通过nleippe，包含一个递归实现，看起来很有希望（我修改了第三行做任何非数组值字符串比较）：

One of the user-contributed notes, by nleippe, contains a recursive implementation that looks promising (I modified the third line to do string comparison on any non-array values):

function array_intersect_assoc_recursive(&$arr1, &$arr2) {
    if (!is_array($arr1) || !is_array($arr2)) {
//      return $arr1 == $arr2; // Original line
        return (string) $arr1 == (string) $arr2;
    }
    $commonkeys = array_intersect(array_keys($arr1), array_keys($arr2));
    $ret = array();
    foreach ($commonkeys as $key) {
        $ret[$key] =& array_intersect_assoc_recursive($arr1[$key], $arr2[$key]);
    }
    return $ret;
}

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