note 124990 deleted from language.oop5.references by cmb

Note Submitter: rnealxp at yahoo dot com ---- Two concise examples that illustrate the true difference between "object-assignment by value" vs "object-assignment by reference": <?php class a{ public $a = 2; } class b{ public $b = 3; } //------------ //Code Set 1 (third line down does not use ampersand(&), it is an object assignment by copy): $a = new a(); $b = new b(); $c = $a; //<--copy by value. echo $c->a . "\n"; //output: 2 $a = $b; //This assignment has no affect on $c. echo $c->a . "\n"; //output: 2 ($c is still a copy of $a, so this works) echo $c->b . "\n"; //output: "Undefined property: a::$b" ($c is still a copy of $a (not $b), so this does not work) //------------ //Code Set 2 (third line down DOES use ampersand(&), it is an object assignment by reference/pointer): $a = new a(); $b = new b(); $c = &$a; //<--copy by reference/pointer. echo $c->a . "\n"; //output: 2 $a = $b; //This assignment replaces $c's underlying object value. echo $c->a . "\n"; //output: "Undefined property: b::$a" ($c is no longer a copy of $a, so this does not work) echo $c->b . "\n"; //output: 3 ($c now points to $b, so this works) //------------ ?>