Call_user_func and call_user_func_array Functions

Today, by accident, I again saw the call_user_func_array () function in php in the official CodeIgniter document. I also encountered this function in the discuz Forum code last year, I checked the usage of this function on the internet today. I would like to share with you the usage of this call_user_func_array and call_user_func functions. In addition, I will provide the usage instructions for func_get_args () and func_num_args () functions.

Call_user_func is used when a function needs to be called dynamically. This function has two usage methods, which are described below:

(1) Call the lonely function:

<? Phpfunction funa ($ B, $ c) {echo $ B; echo $ c;} call_user_func ('funa', "111", "222"); call_user_func ('funa ', "333", "444"); // result output: 111 222 333 444 // have you found that this usage is a bit like the call method in javascript?>

(2) call internal functions of the class:

<?phpclass a{function b(){$args=func_get_args();$num=func_num_args();print_r($args);echo $num;}}call_user_func(array("a","b"),"111","222");?>

In the preceding example, the result is as follows:

Array
(
[0] = & gt; 111
[1] => 222.
)
2

Tip: The func_get_args () function is used to obtain the parameters passed in to the function. An array is returned. The func_num_args () function gets the number of parameters in the input function.

Next let's take a look at call_user_func_array. This function is also used when a function needs to be called dynamically. Its usage is similar to that of the call_user_func function, but the parameter is passed in an array. The example is as follows:

<? Phpfunction a ($ B, $ c) {echo $ B; echo $ c;} call_user_func_array ('A', array ("111", "222 ")); // result output: 111 222?>

The call_user_func_array function can also call internal methods of the class, such:

<? PhpClass ClassA {function bc ($ B, $ c) {$ bc = $ B + $ c; echo $ bc ;}} call_user_func_array (array ('classa ', 'bc'), array ("111", "222"); // result output: 333?>

The following is an example of dynamic function call:

<? Phpfunction otest1 ($ a) {echo ('one parameter');} function otest2 ($ a, $ B) {echo ('two parameters ');} function otest3 ($ a, $ B, $ c) {echo ('Three thes');} function otest () {$ args = func_get_args (); $ num = func_num_args (); call_user_func_array ('test '. $ num, $ args);} otest ("11"); otest ("11", "22"); otest ("11", "22 ", "33");?>

The readers of the above examples can be more impressed when they can run them on their own.

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