Introduction
In this article I will explain references in PHP. References are not pointers. In PHP references are a way to access the same variable content using a different name. PHP reference are not like C pointers,
for instance, you cannot perform pointer arithmetic using them, they are not actual memory addresses. There are three basic operations performed using references, such as assigning by reference, passing by reference, and returning by reference. and so on.
Example
<?php
$foo = 'Hello';
$bar = 'World';
echo $foo."<br>";
echo $bar;
?>
Output
![references2.jpg]()
![references1.jpg]()
<?php
$bar = & $foo;
?>
![references3.jpg]()
Returning References
The following is an example of passing arguments to a function by reference:
Example
<?php
function inc(& $b) {
$b++;
}
$a = 1;
inc($a);
echo $a;
?>
Output
![references5.jpg]()
References are not pointers. In other words, the following constructs what you expect (a function may return a reference to data as opposed to a copy):
<?php
function & get_data() {
$data = "Hello World";
return $data;
}
$foo = & get_data();
?>
Example
The following is an example of using references with undefined variables:
<?php
function foo(&$var)
{ }
foo($a);
$b = array();
foo($b['b']);
var_dump(array_key_exists('b', $b));
$c = new StdClass;
foo($c->d);
var_dump(property_exists($c, 'd'));
?>
Output
![references4.jpg]()