PHP求两个数组的交集

<?php
    $arr1 = array(1, 3, 5, 8, 9);
    $arr2 = array(1, 3, 4, 7, 9);
    $intersaction= array();
    foreach($arr1 as $val) {
        if(in_array($val, $arr2)) $intersaction[] = $val;
    }
    
    var_dump($intersaction);
?>

输出

array(3) { [0]=> int(1) [1]=> int(3) [2]=> int(9) }