Php 我可以通过使数组等于另一个数组来分配数组吗？

我有一个数组

$x

，元素数为非零。我想创建另一个数组（

$y

），它等于

$x

。然后我想使用

$y

进行一些操作，而不引起对

$x

的任何更改。我可以这样创建

$y

：

$y = $x;

---

换句话说，如果我修改以上述方式创建的

$y

，我会更改

$x

的值吗？

否，副本不会更改原件

如果使用对原始数组的引用，则会更改它：

$a = array(1,2,3,4,5);
$b = &$a;
$b[2] = 'AAA';
print_r($a);

让我们试一试：

$a = array(0,1,2);
$b = $a;
$b[0] = 5;

print_r($a);
print_r($b);

给予

报告说：

数组赋值总是涉及值复制。使用引用运算符按引用复制数组

---

数组是按值复制的。这里有一个gotchatho。如果某个元素是引用，则复制该引用，但引用同一对象

<?php
class testClass {
    public $p;
    public function __construct( $p ) {
        $this->p = $p;
    }
}

// create an array of references
$x = array(
    new testClass( 1 ),
    new testClass( 2 )
);
//make a copy
$y = $x;

print_r( array( $x, $y ) );
/*
both arrays are the same as expected
Array
(
    [0] => Array
        (
            [0] => testClass Object
                (
                    [p] => 1
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

    [1] => Array
        (
            [0] => testClass Object
                (
                    [p] => 1
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

)
*/

// change one array
$x[0]->p = 3;

print_r( array( $x, $y ) );
/*
the arrays are still the same! Gotcha
Array
(
    [0] => Array
        (
            [0] => testClass Object
                (
                    [p] => 3
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

    [1] => Array
        (
            [0] => testClass Object
                (
                    [p] => 3
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

)
*/

---

天哪！这太容易测试了。。。写这些问题所需的时间比写一个简单的测试来了解你想知道的要多，你把PHP和python搞混了。

<?php
class testClass {
    public $p;
    public function __construct( $p ) {
        $this->p = $p;
    }
}

// create an array of references
$x = array(
    new testClass( 1 ),
    new testClass( 2 )
);
//make a copy
$y = $x;

print_r( array( $x, $y ) );
/*
both arrays are the same as expected
Array
(
    [0] => Array
        (
            [0] => testClass Object
                (
                    [p] => 1
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

    [1] => Array
        (
            [0] => testClass Object
                (
                    [p] => 1
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

)
*/

// change one array
$x[0]->p = 3;

print_r( array( $x, $y ) );
/*
the arrays are still the same! Gotcha
Array
(
    [0] => Array
        (
            [0] => testClass Object
                (
                    [p] => 3
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

    [1] => Array
        (
            [0] => testClass Object
                (
                    [p] => 3
                )

            [1] => testClass Object
                (
                    [p] => 2
                )

        )

)
*/