A brief discussion on the call_user_func() and call_user_func_array() functions in PHP

This article mainly gives a brief explanation of the functions and usage of the call_user_func() and call_user_func_array() functions in PHP. Friends who are interested can learn about it.

call_user_func: Call a parameter as a callback function

Usage instructions:

call_user_func ( callable $callback [, mixed $parameter [, mixed $... ]] ) : mixed

Parameter description:

First parameter $callback serves as the callback function, and other parameters are parameters of the callback function.

$parameter: The parameter passed in to the callback $callback function. Note that the parameters here cannot be passed by reference.

The following simple examples illustrate the use of call_user_func in different situations:

//先引用，后执行
function _call($call){
    echo $call++.&#39;<br/>&#39;;
    echo $call++.&#39;<br/>&#39;;
    return $call;
}
$rs = call_user_func(&#39;_call&#39;,1);
var_dump($rs);

//结果
//1
//2
//int(3)

Execute first, then reference

$arg = 1;
call_user_func(function ($call){
    echo ++$call.&#39;<br/>&#39;;
    echo ++$call.&#39;<br/>&#39;;
},$arg);

//结果为2，3

The callback function does not pass a value, and passes func_get_arg and func_get_args gets parameters

$argOne = 1;
$argTwo = 2;
call_user_func(function (){
    //获取第几个参数
    $arg = func_get_arg(0);
    var_dump($arg);
    echo &#39;<br/>&#39;;
    //获取所有的参数，并以数组的形式返回
    $args = func_get_args();
    var_dump($args);
    //获取参数个数
    $argNum = func_num_args();
    echo "<br/>";
    var_dump($argNum);
},$argOne,$argTwo);

//结果为
int(1) 
array(2) { [0]=> int(1) [1]=> int(2) } 
int(2)

Calling class methods:

There are two forms of calling static methods in a class, and the first parameter of calling a public method can only be an array

class Func{

    static public function _One(){
        $str = "THE CLASS NAME IS".__CLASS__." AND CLASS STATIC METHOD IS ".__METHOD__;
        $argNum = func_num_args();
        if($argNum){
            $arg = func_get_arg(0);
            return $str.' and argument is '.$arg;
        }else{
            return $str;
        }
    }


    public function _Two($num){
        return $num ? $num + 1 : $num;
    }

}

echo "<br/>";
//调用类的静态方法
var_dump(call_user_func(&#39;Func::_One&#39;,&#39;one&#39;));
echo &#39;<br/>&#39;;
var_dump(call_user_func([&#39;Func&#39;,&#39;_One&#39;]));

$num = 4;
$o = new Func;
//调用类普通方法
$return = call_user_func(array($o,&#39;_Two&#39;),$num);
echo &#39;<br/>&#39;;
var_dump($return);

结果：
string(79) "THE CLASS NAME ISFunc AND CLASS STATIC METHOD IS Func::_One and argument is one" 
string(59) "THE CLASS NAME ISFunc AND CLASS STATIC METHOD IS Func::_One" 
int(5)

When calling a class with a namespace, the usage of call_user_func is the same as above

//调用静态方法
call_user_func(array(__NAMESPACE__.'\StaticDemo','_One'),100);
call_user_func('App\StaticDemo::_One',200);
//调用public方法
call_user_func(array($obj,'_Two'),2,3,4);　　

Finally:
Similar to the call_user_func function, there is call_user_func_array, the function of call_user_func_array is the same as call_user_func The function is the same,
The difference is that call_user_func uses a callback function to process characters, while call_user_func_array uses a callback function to process arrays, which means that the second parameter of call_user_func_array can only be an array.

Related tutorials: PHP video tutorial

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