PHP数组交集与差集函数

• array_intersect() : 比较数组的键值（不比较键名），返回交集

$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("e"=>"red","f"=>"green","g"=>"blue");
$newArr = array_intersect($a1, $a2);
print_r($newArr); //Array ( [a] => red [b] => green [c] => blue )

• array_intersect_assoc() : 比较数组的键值和键名，返回交集

$a1 = array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2 = array("a"=>"red","b"=>"green","c"=>"blue");
$newArr = array_intersect_assoc($a1,$a2);
print_r($newArr); //Array ( [a] => red [b] => green [c] => blue )

• array_intersect_key() : 比较数组的键名（不比较键值），返回交集

$a1 = array("a"=>"red","b"=>"green","c"=>"blue");
$a2 = array("a"=>"red","c"=>"blue","d"=>"pink");
$newArr = array_intersect_key($a1,$a2);
print_r($newArr); //Array ( [a] => red [c] => blue )

• array_intersect_ukey() : 使用自定义方法方法比较数组的键名（不比较键值），返回交集

function myfunction($a,$b)
{
    if ($a===$b)
    {
        return 0;
    }
    return ($a>$b)?1:-1;
}

$a1 = array("a"=>"red","b"=>"green","c"=>"blue");
$a2 = array("d"=>"red","b"=>"green","e"=>"blue");
$newArr = array_intersect_ukey($a1, $a2, 'myfunction');
print_r($newArr); //Array ( [b] => green )