Example
Compare the key values of two arrays (use user custom function to compare key values), and return the difference set:
<?php function myfunction($a,$b) { if ($a===$b) { return 0; } return ($a>$b)?1:-1; } $a1=array("a"=>"red","b"=>"green","c"=>"blue"); $a2=array("a"=>"blue","b"=>"black","e"=>"blue"); $result=array_udiff($a1,$a2,"myfunction"); print_r($result); ?>
Definition and usage
array_udiff() function is used to compare the key values of two (or more) arrays and return the difference.
Note: This function uses a user-defined function to compare key values!
This function compares the key values of two (or more) arrays and returns a difference array that includes everything in the compared array (array1), but not in any other parameter array. (array2 or array3, etc.).
Syntax
array_udiff(array1,array2,array3...,myfunction)
Parameters | Description |
array1 | Required. The first array to compare with other arrays. |
array2 | Required. The array to compare to the first array. |
array3,... | Optional. Additional array to compare with the first array. |
myfunction | Required. A string that defines a callable comparison function. If the first argument is <, =, > and the second argument is, the corresponding comparison function must return an integer of <, =, > 0. |
Technical details
Return value: | Returns a difference array, which includes Returns all keys that are in the array being compared (array1), but not in any of the other argument arrays (array2 or array3, etc.). |
PHP Version: | 5.1.0+ |
更多实例
实例 1
比较三个数组的键值(使用用户自定义函数比较键值),并返回差集:
<?php function myfunction($a,$b) { if ($a===$b) { return 0; } return ($a>$b)?1:-1; } $a1=array("a"=>"red","b"=>"green","c"=>"blue","yellow"); $a2=array("A"=>"red","b"=>"GREEN","yellow","black"); $a3=array("a"=>"green","b"=>"red","yellow","black"); $result=array_udiff($a1,$a2,$a3,"myfunction"); print_r($result); ?>
<?php // array_udiff() class Obj { private $code = 0; public function construct($code) { $this->code = intval($code); } public function getCode() { return $this->code; } /** * 该函数必须根据实际情况返回 0, 1, -1 这三种值,才能正确计算出差集 */ public static function cmp($a, $b) { if ($a->getCode() === $b->getCode()) return 0; return $a->getCode() > $b->getCode() ? 1 : -1; } /** * 此种形式是在《深入PHP面向对象模式与实践》一书看到的写法 * 经验证是无效的,具体在第十章讲解组合模式处 */ public static function cmp2($a, $b) { return $a === $b ? 0 : 1; } } $e1 = new Obj('111'); $e2 = new Obj('222'); $e3 = new Obj('333'); $e4 = new Obj('444'); $e5 = new Obj('555'); $e6 = new Obj('666'); $arr = [$e1, $e2, $e3, $e4, $e5, $e6]; $arr2 = [$e2, $e3, $e6]; $arr = array_udiff($arr, $arr2, ['Obj', 'cmp']); // $arr = array_udiff($arr, $arr2, ['Obj', 'cmp2']); // cmp2 这个比较方法无法返回正确结果 var_dump($arr);
array_diff 使用注意:
1. 返回差集中,键名保留不变
2. 两个单元仅在 (string) $elem1 === (string) $elem2 时被认为是相同的。也就是说,当字符串的表达是一样的时候。
类似的函数:
array_diff_key
array_diff_ukey
总结:
array_diff, array_udiff 仅根据 value 判断
array_diff_key, array_diff_ukey 仅根据 key 判断
array_diff_assoc, array_diff_uassoc, array_udiff_assoc, array_udiff_uassoc 根据 key和value 一起来判断
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