php函数current和next

<?php
$people = array("Bill", "Steve", "Mark", "David");

echo current($people) . "<br>";
echo next($people);
#输出结果
Bill
Steve

$arr1 = array(XXXX);
$arr2 = array(XXXX);

$res = array();
$notId = array();

foreach ($arr2 as $key2 => $val2) {
    $res[$val2] = (int) current($arr1); //每次循环时返回arr1的当前值
    if (current($arr1) == false) {
        $notId[] = $val2;
    }
    next($arr1);//将arr1的指针移到下一个值
}