array_diff_key()

(PHP 5 >= 5.1.0, PHP 7)

使用键名比较计算数组的差集

说明

array_diff_key(array $array1,array $array2[,array $...]): array

根据$array1中的键名和$array2进行比较，返回不同键名的项。本函数和array_diff()相同只除了比较是根据键名而不是值来进行的。

参数

$array1

从这个数组进行比较

$array2

针对此数组进行比较

更多比较数组

返回值

array_diff_key()返回一个数组，该数组包括了所有出现在$array1中但是未出现在任何其它参数数组中的键名的值。

范例

Example #1array_diff_key()例

在key => value对中的两个键名仅在(string)$key1 ===(string)$key2时被认为相等。换句话说，执行的是严格类型检查，因此字符串的表达必须完全一样。

<?php
$array1 = array('blue'  => 1, 'red'  => 2, 'green'  => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'   => 8);
var_dump(array_diff_key($array1, $array2));
?>

以上例程会输出：

array(2) {
  ["red"]=>
  int(2)
  ["purple"]=>
  int(4)
}

注释

Note:

注意本函数只检查了多维数组中的一维。当然，可以用array_diff_key($array1[0],$array2[0]);来检查更深的维度。

参见

• array_diff() 计算数组的差集
• array_udiff() 用回调函数比较数据来计算数组的差集
• array_diff_assoc() 带索引检查计算数组的差集
• array_diff_uassoc() 用用户提供的回调函数做索引检查来计算数组的差集
• array_udiff_assoc() 带索引检查计算数组的差集，用回调函数比较数据
• array_udiff_uassoc() 带索引检查计算数组的差集，用回调函数比较数据和索引
• array_diff_ukey() 用回调函数对键名比较计算数组的差集
• array_intersect() 计算数组的交集
• array_intersect_assoc() 带索引检查计算数组的交集
• array_intersect_uassoc() 带索引检查计算数组的交集，用回调函数比较索引
• array_intersect_key() 使用键名比较计算数组的交集
• array_intersect_ukey() 用回调函数比较键名来计算数组的交集

To return the unique elements (those with a key that exists only once in either array but not in both) try:
function array_unique_diff ($array1, $array2)
{
 array_merge(array_diff_key($array1, $array2), array_diff_key($array2, $array1));
}
Example:
$array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'  => 8);
 array_diff_key($array1, $array2)
returns
 array ( 'red' => 2, 'purple' => 4 ) 
 array_diff_key($array2, $array1)
returns
 array ( 'yellow' => 7, 'cyan' => 8, )
 array_unique_diff($array1, $array2);
 
returns
 array ( 'red' => 2, 'purple' => 4, 'yellow' => 7, 'cyan' => 8, )

I needed something a little different where maybe even the keys in multidimensional arrays don't match up. Setting $assoc to false will cause only to check for missing keys, otherwise it compares values as well. This was also based on '2ge at 2ge dot us' function
<?php
function n_array_diff_assoc ($a1, $a2, $assoc=true) {
  $r = array();
  if(is_array(current($a1))):
    foreach($a1 as $k => $v):
      if(isset($a2[$k])):
        $diff = n_array_diff($a1[$k], $a2[$k], $assoc);
        if (!empty($diff)):
          $r[$k] = $diff;
        endif;
      else:
        $r[$k] = $v;
      endif;
    endforeach;
  else:
    $r = $assoc ? array_diff_assoc($a1, $a2) : array_diff_key($a1, $a2);
  endif;
  return $r;
}
?>

The PHP4 version below works only unidirectionally. If you switch the arrays around i.e. (ar2, ar1) you get different results than (ar1, ar2).

The recursive function suggested by '2ge at 2ge dot us' will provide you with empty arrays if there's no diff. 
This variant of the function cleans up empty arrays and fixes a bug in the first suggested version. It works 100%
.
<?php
function array_diff_key_recursive ($a1, $a2) {
    foreach($a1 as $k => $v) {
      //$r[$k] = is_array($v) ? $this->array_diff_key_recursive($a1[$k], $a2[$k]) : array_diff_key($a1, $a2);
    if (is_array($v))
      {
      $r[$k]=$this->array_diff_key_recursive($a1[$k], $a2[$k]);
      }else
      {
      $r=array_diff_key($a1, $a2);
      }
    if (is_array($r[$k]) && count($r[$k])==0)
      {
      unset($r[$k]);
      }
    }
    return $r;
  }
?>

Seems to be a great function, especially for n-dimensions arrays. The only problem is that I cannot find it in php 5.0.3 and 5.0.4. Does it really exist ?! :(
[20:27:05][maxence@conurb] ~/test2/php-5.0.4$ grep PHP_FUNCTION * -r | grep -i array_diff_key 
[20:27:09][maxence@conurb] ~/test2/php-5.0.4$

Improved recursive version.
<?php
/**
 * @author Gajus Kuizinas <gk@anuary.com>
 * @version 1.0.0 (2013 03 19)
 */
function array_diff_key_recursive (array $arr1, array $arr2) {
  $diff = array_diff_key($arr1, $arr2);
  $intersect = array_intersect_key($arr1, $arr2);
  
  foreach ($intersect as $k => $v) {
    if (is_array($arr1[$k]) && is_array($arr2[$k])) {
      $d = array_diff_key_recursive($arr1[$k], $arr2[$k]);
      
      if ($d) {
        $diff[$k] = $d;
      }
    }
  }
  
  return $diff;
}
?>
An up to date version is maintained at https://github.com/gajus/flow/blob/master/flow.inc.php#L337.

Well, you could implement in the code something more powerfull: 
http://www.php.net/manual/en/function.array-diff.php#31364

Here's a simple function that returns true if all keys in the first array are found in the second array, and false if they aren't.
function same_keys ($a1, $a2) {
  $same = false;
  if (!array_diff_key($a1, $a2)) {
    $same = true;
    foreach ($a1 as $k => $v) {
      if (is_array($v) && !same_keys($v, $a2[$k])) {
        $same = false;
        break;
      }
    }
  }
  return $same;
}
To check if two arrays have the same structure, ignoring values, execute the function twice, the second time with the arguments reversed.

One more alternative variant :)
<?
if (!function_exists('array_diff_key')) {
  function array_diff_key() {
    $argCount  = func_num_args();
    $diff_arg_prefix = 'diffArg';
    $diff_arg_names = array();
    for ($i=0; $i < $argCount; $i++) {
      $diff_arg_names[$i] = 'diffArg'.$i;
      $$diff_arg_names[$i] = array_keys((array)func_get_arg($i));
    }
    $diffArrString = '';
    if (!empty($diff_arg_names)) $diffArrString = '$'.implode(', $', $diff_arg_names);
    eval("\$result = array_diff(".$diffArrString.");");
    return $result;
  }
}
?>

you can use this function for return the difference of two array !
<?php
function array_unique_diff_key ($array1, $array2)
{
 if (is_array($array1) && is_array($array2))
  return array_diff_key($array1, $array2) + array_diff_key($array2, $array1);
 else if (is_array($array1)) return $array1;
 else if (is_array($array2)) return $array2;
 else return array();
}
?>

Hello, if you need diff key of n-dimensional arrays here is nice solution:
<?php
function n_array_diff ($a1, $a2) {
    foreach($a1 as $k => $v) {
      $r[$k] = is_array($v) ? n_array_diff($a1[$k], $a2[$k]) : array_diff_key($a1, $a2);
    }
    return $r;
}
?>
it will print everything, what is missing in $a2.