检查一个数组的元素是否在PHP中的另一个数组中

Question

我在PHP中有两个数组,如下所示:

人:

Array
(
    [0] => 3
    [1] => 20
)

诚征罪犯:

Array
(
    [0] => 2
    [1] => 4
    [2] => 8
    [3] => 11
    [4] => 12
    [5] => 13
    [6] => 14
    [7] => 15
    [8] => 16
    [9] => 17
    [10] => 18
    [11] => 19
    [12] => 20
)

如何检查是否所有的的人们元素是在通缉犯阵列？

在这个例子中,它应该返回,true因为20在Wanted Criminals中.

提前致谢.

Answer 1

你可以用array_intersect().

$result = !empty(array_intersect($people, $criminals));

Answer 2

使用array_intersect()和count()(而不是空)没有什么问题.

例如:

$bFound = (count(array_intersect($criminals, $people))) ? true : false;

Answer 3

如果'空'不是最好的选择,那么这个:

if (array_intersect($people, $criminals)) {...} //when found

要么

if (!array_intersect($people, $criminals)) {...} //when not found

Answer 4

该代码无效,因为您只能将变量传递给语言结构.empty()是一种语言结构.

你必须分两行:

$result = array_intersect($people, $criminals);
$result = !empty($result);

Answer 5

in_array与array_intersect的性能测试:

$a1 = array(2,4,8,11,12,13,14,15,16,17,18,19,20);

$a2 = array(3,20);

$intersect_times = array();
$in_array_times = array();
for($j = 0; $j < 10; $j++)
{
    /***** TEST ONE array_intersect *******/
    $t = microtime(true);
    for($i = 0; $i < 100000; $i++)
    {
        $x = array_intersect($a1,$a2);
        $x = empty($x);
    }
    $intersect_times[] = microtime(true) - $t;


    /***** TEST TWO in_array *******/
    $t2 = microtime(true);
    for($i = 0; $i < 100000; $i++)
    {
        $x = false;
        foreach($a2 as $v){
            if(in_array($v,$a1))
            {
                $x = true;
                break;
            }
        }
    }
    $in_array_times[] = microtime(true) - $t2;
}

echo '<hr><br>'.implode('<br>',$intersect_times).'<br>array_intersect avg: '.(array_sum($intersect_times) / count($intersect_times));
echo '<hr><br>'.implode('<br>',$in_array_times).'<br>in_array avg: '.(array_sum($in_array_times) / count($in_array_times));
exit;

结果如下:

0.26520013809204
0.15600109100342
0.15599989891052
0.15599989891052
0.1560001373291
0.1560001373291
0.15599989891052
0.15599989891052
0.15599989891052
0.1560001373291
array_intersect avg: 0.16692011356354

0.015599966049194
0.031199932098389
0.031200170516968
0.031199932098389
0.031200885772705
0.031199932098389
0.031200170516968
0.031201124191284
0.031199932098389
0.031199932098389
in_array avg: 0.029640197753906

in_array至少快5倍.请注意,我们会在找到结果后立即"中断".