Call the callback given by the first parameter (original) (raw)

call_user_func

(PHP 4, PHP 5, PHP 7)

call_user_func — Call the callback given by the first parameter

Description

Parameters

callback

The callable to be called.

...

Zero or more parameters to be passed to the callback.

Note:

Note that the parameters for call_user_func() are not passed by reference.

Example #1 call_user_func() example and references

<?php error_reporting(E_ALL); function increment(&$var) { $var++; }$a = 0; call_user_func('increment', $a); echo $a."\n";// You can use this instead call_user_func_array('increment', array(&$a)); echo $a."\n"; ?>

The above example will output:

Warning: Parameter 1 to increment() expected to be a reference, value given in … 0 1

Return Values

Returns the return value of the callback.

Changelog

Version Description
5.3.0 The interpretation of object oriented keywords like parent and self has changed. Previously, calling them using the double colon syntax would emit an E_STRICT warning because they were interpreted as static.
5.3.0 If the called function expects a parameter to be passed by reference, anE_WARNING is now issued.

Examples

Example #2 call_user_func() example

<?php function barber($type) { echo "You wanted a $type haircut, no problem\n"; } call_user_func('barber', "mushroom"); call_user_func('barber', "shave"); ?>

The above example will output:

You wanted a mushroom haircut, no problem You wanted a shave haircut, no problem

Example #3 call_user_func() using namespace name

`<?phpnamespace Foobar;

class

Foo {
static public function test() {
print "Hello world!\n";
}
}call_user_func(NAMESPACE .'\Foo::test'); // As of PHP 5.3.0
call_user_func(array(NAMESPACE .'\Foo', 'test')); // As of PHP 5.3.0?> `

The above example will output:

Hello world! Hello world!

Example #4 Using a class method with call_user_func()

<?phpclass myclass { static function say_hello() { echo "Hello!\n"; } }$classname = "myclass";call_user_func(array($classname, 'say_hello')); call_user_func($classname .'::say_hello'); // As of 5.2.3$myobject = new myclass();call_user_func(array($myobject, 'say_hello'));?>

The above example will output:

Example #5 Using lambda function with call_user_func()

<?php call_user_func(function($arg) { print "[$arg]\n"; }, 'test'); /* As of PHP 5.3.0 */ ?>

The above example will output:

Notes

Note:

Callbacks registered with functions such as call_user_func() and call_user_func_array() will not be called if there is an uncaught exception thrown in a previous callback.

See Also