Function arguments
Variables declared as global inside a function are available outside the function.
<?php
function writefunctionvars() {
global $foo;
$foo = "something";
}
writefunctionvars();
echo $foo; // displays "something"
?>
Returning values
Values are returned by using the optional return statement. Any type may be returned, including arrays and objects. This causes the function to end its execution immediately and pass control back to the line from which it was called. See return for more information.
Note:
If the return is omitted the value
NULLwill be returned.
Example #1 Use of return
<?php
function square($num)
{
return $num * $num;
}
echo square(4); // outputs '16'.
?>
A function can not return multiple values, but similar results can be obtained by returning an array.
Example #2 Returning an array to get multiple values
<?php
function small_numbers()
{
return array (0, 1, 2);
}
list ($zero, $one, $two) = small_numbers();
?>
To return a reference from a function, use the reference operator & in both the function declaration and when assigning the returned value to a variable:
Example #3 Returning a reference from a function
<?php
function &returns_reference()
{
return $someref;
}
$newref =& returns_reference();
?>
For more information on references, please check out References Explained.
add a note
User Contributed Notes
Returning values
bbraun at basicbusinesssim dot com
12-Jan-2011 03:43
rstaveley at seseit dot com
29-Aug-2010 01:26
Developers with a C background may expect pass by reference semantics for arrays. It may be surprising that pass by value is used for arrays just like scalars. Objects are implicitly passed by reference.
<?php
# (1) Objects are always passed by reference and returned by reference
class Obj {
public $x;
}
function obj_inc_x($obj) {
$obj->x++;
return $obj;
}
$obj = new Obj();
$obj->x = 1;
$obj2 = obj_inc_x($obj);
obj_inc_x($obj2);
print $obj->x . ', ' . $obj2->x . "\n";
# (2) Scalars are not passed by reference or returned as such
function scalar_inc_x($x) {
$x++;
return $x;
}
$x = 1;
$x2 = scalar_inc_x($x);
scalar_inc_x($x2);
print $x . ', ' . $x2 . "\n";
# (3) You have to force pass by reference and return by reference on scalars
function &scalar_ref_inc_x(&$x) {
$x++;
return $x;
}
$x = 1;
$x2 =& scalar_ref_inc_x($x); # Need reference here as well as the function sig
scalar_ref_inc_x($x2);
print $x . ', ' . $x2 . "\n";
# (4) Arrays use pass by value sematics just like scalars
function array_inc_x($array) {
$array{'x'}++;
return $array;
}
$array = array();
$array['x'] = 1;
$array2 = array_inc_x($array);
array_inc_x($array2);
print $array['x'] . ', ' . $array2['x'] . "\n";
# (5) You have to force pass by reference and return by reference on arrays
function &array_ref_inc_x(&$array) {
$array{'x'}++;
return $array;
}
$array = array();
$array['x'] = 1;
$array2 =& array_ref_inc_x($array); # Need reference here as well as the function sig
array_ref_inc_x($array2);
print $array['x'] . ', ' . $array2['x'] . "\n";
Anonymous
09-Jul-2010 07:54
As of at least PHP 5.3, a function or class method returning an object acts like an object.
<?php
class A {
function test() {
echo "Yay!";
}
}
function get_obj() {
return new A();
}
get_obj()->test(); // "Yay!"
?>
Sorry, still doesn't work with arrays. Ie <?php echo get_array()[1]; ?> fails.
bgalloway at citycarshare dot org
27-Mar-2008 06:27
Be careful about using "do this thing or die()" logic in your return lines. It doesn't work as you'd expect:
<?php
function myfunc1() {
return('thingy' or die('otherthingy'));
}
function myfunc2() {
return 'thingy' or die('otherthingy');
}
function myfunc3() {
return('thingy') or die('otherthingy');
}
function myfunc4() {
return 'thingy' or 'otherthingy';
}
function myfunc5() {
$x = 'thingy' or 'otherthingy'; return $x;
}
echo myfunc1(). "\n". myfunc2(). "\n". myfunc3(). "\n". myfunc4(). "\n". myfunc5(). "\n";
?>
Only myfunc5() returns 'thingy' - the rest return 1.
Trevor Blackbird > yurab.com
18-Apr-2006 04:36
You can also use the compact-extract pair to return multiple values:
<?php
function Composite($x, $y) {
$sum = $x + $y;
$dif = $x - $y;
return compact('sum', 'dif');
}
extract(Composite(3, 4));
echo $sum;
echo $dif;
?>
nick at itomic.com
04-Aug-2003 12:56
Functions which return references, may return a NULL value. This is inconsistent with the fact that function parameters passed by reference can't be passed as NULL (or in fact anything which isnt a variable).
i.e.
<?php
function &testRet()
{
return NULL;
}
if (testRet() === NULL)
{
echo "NULL";
}
?>
parses fine and echoes NULL
rusty at socrates dot berkeley dot edu
17-Jul-2003 02:48
Here's a sick idea. When a function returns no value, if you assign its return value to a variable that variable will be unset. So instead of returning -1 on error just return with no value.
For example,
function myfunc($myvar) {
if ($myvar == "abc")
return(1);
if ($myvar == "xyz")
return(2);
return;
}
$abc = myfunc("def");
if (isset($abc))
echo("a-ok");
else
echo("oops");
LouisGreen at pljg dot freeserve dot co dot uk
25-Mar-2003 10:13
It seems that when you wish to export a varible, you can do it as return $varible, return an array(), or globalise it. If you return something, information for that varible can only travel one way when the script is running, and that is out of the function.
function fn() {
$varible = "something";
return $varible;
}
echo fn();
OR
$newvarible = fn();
Although if global was used, it creates a pointer to a varible, whether it existed or not, and makes whatever is created in the function linked to that global pointer. So if the pointer was global $varible, and then you set a value to $varible, it would then be accessible in the global scope. But then what if you later on in the script redefine that global to equal something else. This means that whatever is put into the global array, the information that is set in the pointer, can be set at any point (overiden). Here is an example that might make this a little clearer:
function fn1() {
global $varible; // Pointer to the global array
$varible = "something";
}
fn1();
echo $varible; // Prints something
$varible = "12345";
echo $varible; // Prints 12345
function fn2() {
global $varible; // Pointer to the global array
echo $varible;
}
fn2(); // echos $varible which contains "12345"
Basically with the global array, you can set it refer to something already defined or set it to something, (a pointer) such as varible you plan to create in the function, and later possibly over ride the pointer with something else.
ian at NO_SPAM dot verteron dot net
15-Jan-2003 04:28
In reference to the poster above, an additional (better?) way to return multiple values from a function is to use list(). For example:
function fn($a, $b)
{
# complex stuff
return array(
$a * $b,
$a + $b,
);
}
list($product, $sum) = fn(3, 4);
echo $product; # prints 12
echo $sum; # prints 7
devinemke at yahoo dot com
26-Jun-2002 11:45
A function can only return one value, but that value can be an array or other compound value. If you want to just define several variables into the global scope within your function you can do two things:
1. return an array from your function and then run the extract() function
$result_array = test ();
extract ($result_array);
2. Or you can just append the variables to the $GLOBALS array:
$array = array ('first' => 'john', 'middle' => 'q', 'last' => 'public');
function upper_case () {
global $array;
foreach ($array as $key => $value)
{
$GLOBALS[$key] = strtoupper ($value);
}
}
upper_case ();
echo "$first $middle $last";
// returns JOHN Q PUBLIC
In this second example you can create multiple values without necessarily returning anything from the function. This may be handy for applying several functions (stripslashes, trim, etc..) accross all elements of $_POST or $_GET and then having all of the newly cleaned up variables extracted out for you.
destes at ix dot netcom dot com dot nospam
03-Mar-2002 12:35
One thing to note about returning arrays- the usual "complex variable" syntax will give you a parse error. For instance, if you have:
function adminstuff() {
mysql_connect('localhost', 'user', 'pass');
mysql_select_db('mydb');
$result = mysql_query('SELECT login, pass FROM users);
$resultrow = mysql_fetch_array( $result );
# this next line is key:
return array ({$resultrow['login']}, {$resultrow['pass']});
}
That won't work. You *can* reference array elements without the curly-braces syntax, i.e.:
return array ($resultrow['login'], $resultrow['pass']);
But you'll get a parse error if you try to use curly braces. Thanks,
Steve
php at control-escape dot com
25-Apr-2001 12:26
PHP functions that do not explicitly return a value will be 'void', that is, they return 'null'. C programmers will be accustomed to this already, but folks coming from Perl may expect the return value of a function to be the return value of the last expression evaluated inside the function, as is the case with Perl. Not so.