Adding data to a reference to change the referenced array in PHP

Question

I have built a function to retrieve the last specified key of an array, it references the array and displays it fine, however, when I try to add to the reference variable, it does not affect the referenced array.

Here is my code:

class test {
    public function __construct() {
        // For testing
        $this->keys[] = 'key1';
        $this->keys[] = 'key2';
        $this->array['key1']['key2'] = 'Hello World';
    }
    protected function &getArray() {
        $array = &$this->array;
        foreach($this->keys as $key) {
            $array = &$array[$key];
        }
        return $array;
    }
    function add() {
        $tmpArray = $this->getArray();
        print_r($tmpArray);
        echo "<br>\n";
        $tmpArray = 'Goodbye World';
        print_r($tmpArray);
        echo "<br>\n";
        print_r($this->array);
    }

}

$test = new test;
$test->add();

To sum it up, add() and __construct() are for testing. I am trying to add to $this->array with add(). However when I specify $tmpArray = 'Goodbye World' the referenced array $this->array['key1']['key2'] is still Hello World.

Could someone help point me in the right direction?

This is mostly a testing class. The most important part is getArray() which references the 'key2' of $this->array since key2 is the last specified in $this->keys. $tmpArray is equal to Hello World from the reference before I set it to Goodbye World. But I am trying to get $this->array['key1']['key2'] to equal Goodbye World too from the reference. — Devon Bessemer
– Devon Bessemer, Commented Dec 5, 2013 at 23:31
Where does $tags exist in the class variables, where does $values exist in the class variables, you must be getting errors? I can't see any variable declarations inside test. — SamV
– SamV, Commented Dec 5, 2013 at 23:33
My fault, that was a bad copy. It should have been keys, and values should have been array. It has been fixed now. — Devon Bessemer
– Devon Bessemer, Commented Dec 5, 2013 at 23:37

aib · Accepted Answer · 2013-12-05 23:50:56Z

1

In order to return references in PHP, you need to use & twice, once in the definition and once more in assignment. You're missing the one in assignment:

$tmpArray = &$this->getArray();

See PHP: Returning References for details and please don't ask why as I'm incapable of generating rationale for PHP behaviour.

edited Dec 5, 2013 at 23:50

answered Dec 5, 2013 at 23:43

aib

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1 Comment

Devon Bessemer Over a year ago

Thank you, I thought I had tried that but apparently not, but it does indeed work.

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