Returning by reference is useful when you want to use a function to find to which variable a reference should be bound. Do not use return-by-reference to increase performance. The engine will automatically optimize this on its own. Only return references when you have a valid technical reason to do so. To return references, use this syntax:
<?phpclass foo { public $value = 42; public function &getValue() { return $this->value; }}$obj = new foo;$myValue = &$obj->getValue(); // $myValue is a reference to $obj->value, which is 42.$obj->value = 2;echo $myValue; // prints the new value of $obj->value, i.e. 2.?>
Note: Unlike parameter passing, here you have to use
&
in both places - to indicate that you want to return by reference, not a copy, and to indicate that reference binding, rather than usual assignment, should be done for $myValue.
Note: If you try to return a reference from a function with the syntax:
return ($this->value);
this will not work as you are attempting to return the result of an expression, and not a variable, by reference. You can only return variables by reference from a function - nothing else.
To use the returned reference, you must use reference assignment:
<?phpfunction &collector() { static $collection = array(); return $collection;}$collection = &collector();$collection[] = 'foo';?>
<?phpfunction &collector() { static $collection = array(); return $collection;}array_push(collector(), 'foo');?>
Note: Note that
array_push(&collector(), 'foo');
will not work, it results in a fatal error.