call_user_func
(PHP 4, PHP 5, PHP 7)
call_user_func — Call the callback given by the first parameter
Description
call_user_func ( callable $callback , mixed ...$args ) : mixed
Calls the callback given by the first parameter and passes the remaining parameters as arguments.
Parameters
-
callback -
The callable to be called.
-
args -
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 $a."\n"; ?>The above example will output:
Warning: Parameter 1 to increment() expected to be a reference, value given in … 0 1
Return Values
Returns the return value of the callback.
Examples
Example #2 call_user_func() example
<?php
function barber($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
<?php
namespace 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()
<?php
class 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:
Hello! Hello! Hello!
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:
[test]
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
- call_user_func_array() - Call a callback with an array of parameters
- is_callable() - Verify that the contents of a variable can be called as a function
- ReflectionFunction::invoke() - Invokes function
- ReflectionMethod::invoke() - Invoke
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/function.call-user-func.php