(PHP 4, PHP 5, PHP 7, PHP 8)
call_user_func — Call the callback given by the first parameter
Calls the callback given by the first parameter and passes
the remaining parameters as arguments.
callbackThe callable to be called.
argsZero 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 $a."\n";
// it is possible to use this instead
call_user_func_array('increment', array(&$a));
echo $a."\n";
// it is also possible to use a variable function
$increment = 'increment';
$increment($a);
echo $a."\n";
?>The above example will output:
Warning: Parameter 1 to increment() expected to be a reference, value given in … 0 1 2
Returns the return value of the callback.
Example #2 call_user_func() example
<?php
function barber($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');
call_user_func(array(__NAMESPACE__ .'\Foo', 'test'));
?>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');
$myobject = new myclass();
call_user_func(array($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');
?>The above example will output:
[test]
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.