Do PHP Objects Use Value or Reference Assignment?

Are Objects in PHP Assigned by Value or Reference?

In PHP, objects are assigned by reference by default. This means that when a variable is assigned an object reference, it points directly to the object in memory. Any changes made to the object through the variable will be reflected in the original object.

Consider the following example:

<code class="php">class Foo
{
    var $value;

    function foo($value)
    {
        $this->setValue($value);
    }

    function setValue($value)
    {
        $this->value = $value;
    }
}

class Bar
{
    var $foos = array();

    function Bar()
    {
        for ($x = 1; $x <= 10; $x++)
        {
            $this->foos[$x] = new Foo("Foo # $x");
        }
    }

    function getFoo($index)
    {
        return $this->foos[$index];
    }

    function test()
    {
        $testFoo = $this->getFoo(5);
        $testFoo->setValue("My value has now changed");
    }
}

$b = new Bar;
echo $b->getFoo(5)->value;
$b->test();
echo $b->getFoo(5)->value;</code>

When the Bar::test() method is executed, it changes the value of the fifth object in the array of Foo objects. This change is reflected in the original object, as seen in the output:

Foo #5
My value has now changed

This behavior is due to the assignment of the object reference to the $testFoo variable. The variable points directly to the object, so any modifications made through the variable will be reflected in the original object.

To assign an object by value instead of reference, you can use the clone keyword:

<code class="php">$testFoo = clone $this->getFoo(5);</code>

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