Detailed explanation of usage examples of php functions call_user_func and call_user_func_array

When I looked at UCenter, there was a function call_user_func. I was puzzled because I thought it was a function defined by myself, but I couldn’t find it anywhere. After searching on Baidu, I found out that call_user_func is Built-in function

The call_user_func function is similar to a special method of calling a function. The method of use is as follows:

function a($b,$c) 
{ 
echo $b; 
echo $c; 
} 
call_user_func('a', "111","222"); 
call_user_func('a', "333","444"); 
//显示 111 222 333 444

It is strange to call the method inside the class, but it is used It is an array. I don’t know how the developers considered it. Of course, new is omitted, which is also full of novelty:

class a { 
function b($c) 
{ 
echo $c; 
} 
} 
call_user_func(array("a", "b"),"111"); 
//显示 111

The call_user_func_array function is very similar to call_user_func, except that the parameters are passed in a different way. Make the structure of parameters clearer:

function a($b, $c) 
{ 
echo $b; 
echo $c; 
} 
call_user_func_array('a', array("111", "222")); 
//显示 111 222

The call_user_func_array function can also call methods inside the class

Class ClassA 
{ 
function bc($b, $c) { 
$bc = $b + $c; 
echo $bc; 
} 
} 
call_user_func_array(array('ClassA','bc'), array("111", "222")); 
//显示 333

Both the call_user_func function and the call_user_func_array function support references, which makes them and Ordinary function calls tend to have consistent functions:

function a(&$b) 
{ 
$b++; 
} 
$c = 0; 
call_user_func('a', &$c); 
echo $c;//显示 1 
call_user_func_array('a', array(&$c)); 
echo $c;//显示 2

Simple usage of call_user_func_array in php

<?php 
function foobar($arg, $arg2) { 
echo FUNCTION, " got $arg and $arg2\n"; 
} 
class foo { 
function bar($arg, $arg2) { 
echo METHOD, " got $arg and $arg2\n"; 
} 
} 
// Call the foobar() function with 2 arguments 
call_user_func_array("foobar", array("one", "two")); 
// Call the $foo->bar() method with 2 arguments 
$foo = new foo; 
call_user_func_array(array($foo, "bar"), array("three", "four")); 
?>

The output of the above routine is similar to:
foobar got one and two
foo::bar got three and four
Example #2 call_user_func_array() using namespace name

<?php 
namespace Foobar; 
class Foo { 
static
 public function test($name) { 
print "Hello {$name}!\n"; 
} 
} 
// As of PHP 5.3.0 
call_user_func_array(NAMESPACE .&#39;\Foo::test&#39;, array(&#39;Hannes&#39;)); 
// As of PHP 5.3.0 
call_user_func_array(array(NAMESPACE .&#39;\Foo&#39;, &#39;test&#39;), array(&#39;Philip&#39;)); 
?>

The output of the above routine is similar to:
Hello Hannes!
Hello Philip!
Example #3 Using lambda function

<?php 
$func = function($arg1, $arg2) { 
return $arg1 * $arg2; 
}; 
var_dump(call_user_func_array($func, array(2, 4))); /* As of PHP 5.3.0 */ 
?>

The above routine will output:
int(8)

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