Is there simple PHP code to distinguish "Passing the object as reference" vs "Passing the object reference as value"?
This is related to question: How does the "&" operator work in a PHP function?
Is there simple code to show the difference between
passing the object as reference
vs
passing the object's reference as value?
You can pass a variable to a function by reference. This function will be able to modify the original variable.
You can define the passage by reference in the function definition:
<?php
function changeValue(&$var)
{
$var++;
}
$result=5;
changeValue($result);
echo $result; // $result is 6 here
?>
<?php
class X {
var $abc = 10;
}
class Y {
var $abc = 20;
function changeValue(&$obj){//1>here the object,$x is a reference to the object,$obj.hence it is "passing the object's reference as value"
echo 'inside function :'.$obj->abc.'<br />';//2>it prints 10,bcz it accesses the $abc property of class X, since $x is a reference to $obj.
$obj = new Y();//but here a new instance of class Y is created.hence $obj became the object of class Y.
echo 'inside function :'.$obj->abc.'<br />';//3>hence here it accesses the $abc property of class Y.
}
}
$x = new X();
$y = new Y();
$y->changeValue($x);//here the object,$x is passed as value.hence it is "passing the object as value"
echo $x->abc; //4>As the value has been changed through it's reference ,hence it calls $abc property of class Y not class X.though $x is the object of class X
?>
o / p：
inside function :10
inside function :20
20
这个怎么样：
<?php
class MyClass {
public $value = 'original object and value';
}
function changeByValue($originalObject) {
$newObject = new MyClass();
$newObject->value = 'new object';
$originalObject->value = 'changed value';
// This line has no affect outside the function, and is
// therefore redundant here (and so are the 2 lines at the
// the top of this function), because the object
// "reference" was passed "by value".
$originalObject = $newObject;
}
function changeByReference(&$originalObject) {
$newObject = new MyClass();
$newObject->value = 'new object';
$originalObject->value = 'changed value';
// This line changes the object "reference" that was passed
// in, because the "reference" was passed "by reference".
// The passed in object is replaced by a new one, making the
// previous line redundant here.
$originalObject = $newObject;
}
$object = new MyClass();
echo $object->value; // 'original object and value';
changeByValue($object)
echo $object->value; // 'changed value';
$object = new MyClass();
echo $object->value; // 'original object and value';
changeByReference($object)
echo $object->value; // 'new object';