func_get_arg()

(PHP 4, PHP 5, PHP 7)

返回参数列表的某一项

说明

从用户自定义函数的参数列表中获取某个指定的参数。

该函数可以配合func_get_args()和func_num_args()一起使用，从而使得用户自定义函数可以接受自定义个数的参数列表。

参数

参数的偏移量。函数的参数是从0开始计数的。

返回值

返回指定的参数，错误则返回FALSE。

更新日志

错误／异常

当在自定义函数的外面调用的该函数的时候会发出一个警告，或者是当$arg_num比实际传入的参数的数目大的时候也会发出一个警告。

范例

Example #1func_get_arg()例子

Example #2func_get_arg()PHP 5.3 前后对比的例子

test.php

fga.inc 

PHP 5.3 版本之前的输出：

'Second arg'

PHP 5.3 和之后的版本的输出:

Warning: func_get_arg():  Called from the global scope - no function
context in /home/torben/Desktop/code/ml/fga.inc on line 3
false

Example #3func_get_arg()example of byref and byval arguments

以上例程会输出：

注释

因为函数依赖于当前作用域以确定参数的细节，所以在5.3.0 以前的版本中不能用作函数的参数。如必须传递此值时，可将结果赋与一个变量，然后用此变量进行传递。Note:

如果参数以引用方式传递，函数对该参数的任何改变将在函数返回后保留。

Note:This function returns a copy of the passed arguments only, and does not account for default (non-passed) arguments.

参见

• func_get_args() 返回一个包含函数参数列表的数组
• func_num_args()Returns the number of arguments passed to the function

This functions seems so powerful... just when i saw it i thought about writing a fast average of n numbers function so here it is, it is very simple... example usage included. 

func_get_arg() returns a *copy* of the argument, to my knowledge there is no way to retrieve references to a variable number of arguments.
I have a module system in my game at http://lotgd.net where I'd like to be able to pass a variable number of arguments to functions in a module, and pass them by reference if the module asks for it by reference, but you can't accept optional parameters as references, nor can you retrieve the reference on a variable number of arguments. Looks like my modules will have to do with out the ability to accept parameters to their functions by reference.

func_get_arg() does not appear to be allowed to be used as a function argument itself within class constructors in PHP 5.0.2 (wonk-ay!!!):

The above script generates:
Fatal error: func_get_arg(): Can't be used as a function parameter in c:\Inetpub\wwwroot\phpwasrc\chapter10\xxx.php on line 23
There are, however, no problems when passing these as parameters to regular functions.

I actually think that there is need for such "do absolutely everything" functions. I use them mostly as tools for rapid prototyping.
And there is a method with which you may be able to pass several strings to a function: ereg();
Another use for such functions is to create little code snippets for other people out there. They won't have to edit the function any longer if they do not use a parameter. They just don't name it when calling the function.
This results in allrounder functions that are very robust in their use.Normally you just have a little code snippet (e.g. ip-blocking snippets). Through this type of programming you have whole functions.

鹏仔微信 15129739599 鹏仔QQ344225443 鹏仔前端 pjxi.com 共享博客 sharedbk.com