<?php
/*数组(Array) 的赋值总是会涉及到值的拷贝。使用引用运算符通过引用来拷贝数组。*/
$arr1 = array(2, 3);
var_dump($arr1);
$arr2 = $arr1;
$arr2[] = 4; // $arr2 is changed,
// $arr1 is still array(2, 3)
var_dump($arr2);
$arr3 = &$arr1;
$arr3[] = 4; // now $arr1 and $arr3 are the same

var_dump($arr3);
var_dump($arr1);

使用引用运算符通过引用来拷贝数组