Object (into Array) variables in PHP

Question

Here is the code:

$obj = new stdClass;
$obj->AAA = "aaa";
$obj->BBB = "bbb";

$arr = array($obj, $obj);

print_r($arr);

$arr[1]->AAA = "bbb";
$arr[1]->BBB = "aaa";

print_r($arr);

And here is the output:

Array
(
    [0] => stdClass Object
        (
            [AAA] => aaa
            [BBB] => bbb
        )

    [1] => stdClass Object
        (
            [AAA] => aaa
            [BBB] => bbb
        )

)

Array
(
    [0] => stdClass Object
        (
            [AAA] => bbb
            [BBB] => aaa
        )

    [1] => stdClass Object
        (
            [AAA] => bbb
            [BBB] => aaa
        )

)

Can anybody explain to me why all object variables (that are in array) are changed?

And sorry for my bad english. I am not a native english speaker.

score 3 · Accepted Answer · 2012-01-15 18:24:53Z

3

The array is storing two references to the same object, not two distinct objects, as represented below:

array(
    0 =>  ---|          stdClass
             |------->     [AAA] => bbb
    1 =>  ---|             [BBB] => aaa
)

If you want to copy an object, use clone, which performs a shallow copy of the object:

$arr = array($obj, clone $obj);

edited Jan 15, 2012 at 18:24

answered Jan 15, 2012 at 18:19

user142162

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Comments

Alex M · Accepted Answer · 2012-01-15 18:20:02Z

0

You need to create a new instance of the class

$obj2 = new stdClass;
$obj2->AAA = "bbb";
$obj2->BBB = "aaa";

$arr = array($obj, $obj2);

Otherwise your array contains 2 pointers to the same object. The update statement changes the underlying object.

answered Jan 15, 2012 at 18:20

Alex M

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