Passing Objects as parameters in PHP

Objects are Passed by reference by default:

By default the php objects are passed by reference below example will make it more clear. that is why when we copy object it property's are pointing to the same reference

class A {
    public $foo = 1;
} 
$a = new A;$b = $a;     // $a and $b are copies of the same identifier
             // ($a) = ($b) = 
$b->foo = 2;
echo $a->foo."\n";  //this will output 2 as the reference is copied
                    //$a and $b is point to the same location

$c = new A;$d = &$c;    // $c and $d are references
             // ($c,$d) = 
$d->foo = 2;
echo $c->foo."\n";

$e = new A;

function foo($obj) {
    // ($obj) = ($e) = 
    $obj->foo = 2;
}
foo($e);
echo $e->foo."\n";
?>

the output of the above sample example will
2
2
2



/*
 * Created on Oct 24, 2012
 *
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 */

 class ClassTesting {
 
  private $foo;
 
  function __construct($foo){
  $this->foo = $foo;
  }
 
  private function ent($foo){
  $this->foo = $foo;
  }
 
  public function ret($obj){
  $obj->foo = 'this';
  var_dump($obj->foo);
  }
 }

 $x = new ClassTesting("man");
 $a = new ClassTesting("dog");
 $x->ret($a);

?>