Analysis of call_user_func function and call_user_func_array function

Analysis of call_user_func function and call_user_func_array function_PHP tutorial

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Release： 2016-07-13 10:31:19

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Today by chance, I saw the call_user_func_array() function in PHP again in the official documentation of CodeIgniter. I also encountered it in the code of the discuz forum last year. I checked this function online today. Usage, let's share with you the usage of the call_user_func_array and call_user_func functions, and also provide usage instructions for the func_get_args() function and func_num_args() function.

The call_user_func function is used when a function needs to be called dynamically. This function has two uses, which are explained below:

(1) Call the lonely function:

<?php
function funa($b,$c){
	echo $b;
	echo $c;
}
call_user_func('funa',"111","222");
call_user_func('funa',"333","444");
//结果输出：111 222 333 444
//大家有没有发现，这个用法有点像javascript中的call方法
?>

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(2) Call the function inside the class:

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

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For the above example, the output is as follows:

Array
(
[0] => 111
[1] => 222
)
2

Tip: The func_get_args() function gets the parameters passed into the function and returns an array. The func_num_args() function gets the number of parameters passed into the function.

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 the call_user_func function, except that the parameter is passed in an array. The example is as follows:

<?php
function a($b,$c){
	echo $b;echo $c;
}
call_user_func_array('a',array("111","222"));
//结果输出：111 222
?>

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The call_user_func_array function can also call methods inside the class, such as:

<?php
Class ClassA{
	function bc($b,$c){
		$bc=$b + $c;echo $bc;
	}
}
call_user_func_array(array('ClassA','bc'),array("111","222"));
//结果输出：333
?>

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Let’s look at another example of dynamically calling a function:

<?php
function otest1 ($a){
	echo( '一个参数' );
}
function otest2 ( $a,$b){
	echo( '二个参数' );
}
function otest3 ( $a ,$b,$c){
	echo( '三个啦' );
}
function otest (){
	$args=func_get_args();
	$num=func_num_args();
	call_user_func_array( 'otest'.$num,$args  );
}
otest("11");
otest("11","22");
otest("11","22","33");
?>

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Readers can run the above examples themselves and the impression will be even more profound.

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