Are multiple variable assignments done by value or reference?

Question

$a = $b = 0;

In the above code, are both $a and $b assigned the value of 0, or is $a just refer

Answer 1

It depends what're you assigning.

If you're assigning a value, then the assignment copies the original variable to the new one.

_{Example 1:}

$a = $b = 0;
$b++; echo $a;

Above code will return 0 as it's assignment by value.

_{Example 2:}

$a = ($b = 4) + 5; // $a is equal to 9 now, and $b has been set to 4.

An exception to the usual assignment by value behaviour within PHP occurs with objects, which are assigned by reference in PHP 5 automatically. Objects may be explicitly copied via the clone keyword.

_{Example 3}

$a = $b = $c = new DOMdocument();
$c->appendChild($c->createElement('html'));
echo $a->saveHTML();

Above code will print .