Detailed explanation of three examples of calling user-defined functions in PHP

There are custom functions in php. The call_user_func function, call_user_func_array function, and call_user_func function are often used.

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

<?php
//call_user_func函数

function a($b,$c)   
{   
echo $b;   
echo $c;   
}   
call_user_func(&#39;a&#39;, "111","222");   
call_user_func(&#39;a&#39;, "333","444");   
//显示 111 222 333 444   
?>

It is strange to call the method inside the class. Array is used, and the new operation is omitted. Saves resources to a certain extent:

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

2. The call_user_func_array function is very similar to call_user_func, except that the parameters are passed in a different way to make the parameter structure clearer.
For example:

<?php
//call_user_func_array 调用自定义函数

function a($b, $c)   
{   
echo $b;   
echo $c;   
}   
call_user_func_array(&#39;a&#39;, array("111", "222"));   
//显示 111 222   
?>

The call_user_func_array function can also call methods inside the class.
For example:

<?php
Class ClassA   
{
function bc($b, $c) {   
     $bc = $b + $c;   
echo $bc;   
}   
}   
call_user_func_array(array(&#39;ClassA&#39;,&#39;bc&#39;), array("111", "222"));   
//显示 333   
?>

3, both the call_user_func function and the call_user_func_array function support quotes, which makes them more functionally consistent with ordinary function calls:

<?php
//call_user_func函数 调用自定义函数

function a($b)   
{   
$b++;   
}   
$c = 0;   
call_user_func(&#39;a&#39;, $c);   
echo $c;//显示 1   
call_user_func_array(&#39;a&#39;, array($c));   
echo $c;//显示 2  
?>

In addition, both the call_user_func function and the call_user_func_array function support references.

<?php
function increment(&$var)
{
    $var++;
}
$a = 0;
call_user_func(&#39;increment&#39;, $a);
echo $a; // 0
call_user_func_array(&#39;increment&#39;, array(&$a)); // You can use this instead
echo $a; // 1
?>

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