php 自定义函数大全

1. call_user_func和call_user_func_array

以上两个函数以不同的参数形式调用函数。见如下示例：
<?php

class demo
{
public static function action1()
{
echo "This is demo::action1.<br>";
}

public function action2()
{
echo "This is demo::action2.<br>";
}

public function actionWithArgs($arg1, $arg2)
{
echo 'This is demo::actionWithArgs with ($arg1 = ' . $arg1 . ' and $arg2 = ' . $arg2 . ").<br>";
}
}

$demo = new demo();
call_user_func(array("demo", "action1"));
call_user_func(array($demo, "action2"));
call_user_func(array($demo, "actionWithArgs"), "hello", "world");
call_user_func_array(array($demo, "actionWithArgs"), array("hello2", "world2"));

运行结果如下：

This is demo::action1.
This is demo::action2.
This is demo::actionWithArgs with ($arg1 = hello and $arg2 = world).
This is demo::actionWithArgs with ($arg1 = hello2 and $arg2 = world2).

2. func_get_args、func_num_args和func_get_args

这三个函数的共同特征是都很自定义函数参数相关，而且均只能在函数内使用，比较适用于可变参数的自定义函数。他们的函数原型和简要说明如下：
int func_num_args (void) 获取当前函数的参数数量。
array func_get_args (void) 以数组的形式返回当前函数的所有参数。
mixed func_get_arg (int $arg_num) 返回当前函数指定位置的参数，其中0表示第一个参数。

<?php
function demoA()
{
$numOfArgs = func_num_args();
$args = func_get_args();
echo "The number of args in demoA is " . $numOfArgs . "<br>";
for ($i = 0; $i < $numOfArgs; $i++) {
echo "The {$i}th arg is " . func_get_arg($i) . "<br>";
}
echo "-------------------------------------------<br>";
foreach ($args as $arg) {
echo "$arg<br>";
}
}

demoA('hello', 'world', '123456');

运行结果如下：

The number of args in demoA is 3
The 0th arg is hello
The 1th arg is world
The 2th arg is 123456
-------------------------------------------
hello
world
123456

3. register_shutdown_function

函数原型和简要说明如下：

void register_shutdown_function (callable $callback [, mixed $parameter [, mixed $... ]]) 在脚本结束之前或者是中途调用exit时调用改注册的函数。另外，如果注册多个函数，那么他们将会按照注册时的顺序被依次执行，如果其中某个回调函数内部调用了exit()，那么脚本将立刻退出，剩余的回调均不会被执行。

<?php
function myShutdown($arg1, $arg2)
{
echo '$arg1 = ' . $arg1 . ', $arg2 = ' . $arg2 . "<br>";
}

if (function_exists('myShutdown')) {
print "myShutdown function exists now.<br>";
}

register_shutdown_function('myShutdown', 'Hello', 'World');
print "This test is executed.<br>";
exit();
echo "This comments cannot be output.<br>";

运行结果如下：

myShutdown function exists now.
This test is executed.
$arg1 = Hello, $arg2 = World