//比较数组差异
$arr = [1,2,3,4];
$arr1 = [1,2,3];
$diff = array_diff($arr, $arr1);
dump($diff);
//打印输出如下，函数第二个参数为参数值，没有差异则返回空数组
array(1) {
  [3] => int(4)
}