func_get_arg

(PHP 4, PHP 5, PHP 7)

func_get_argReturn an item from the argument list

Опис

mixed func_get_arg ( int $arg_num )

Gets the specified argument from a user-defined function's argument list.

This function may be used in conjunction with func_get_args() and func_num_args() to allow user-defined functions to accept variable-length argument lists.

Параметри

arg_num

The argument offset. Function arguments are counted starting from zero.

Значення, що повертаються

Returns the specified argument, or FALSE on error.

Журнал Змін

Версія Опис
5.3.0 This function can now be used in parameter lists.
5.3.0 If this function is called from the outermost scope of a file which has been included by calling include or require from within a function in the calling file, it now generates a warning and returns FALSE.

Помилки/Винятки

Generates a warning if called from outside of a user-defined function, or if arg_num is greater than the number of arguments actually passed.

Приклади

Приклад #1 func_get_arg() example

<?php
function foo()
{
     
$numargs func_num_args();
     echo 
"Number of arguments: $numargs\n";
     if (
$numargs >= 2) {
         echo 
"Second argument is: " func_get_arg(1) . "\n";
     }
}

foo(123);
?>

Наведений вище приклад виведе:

Number of arguments: 3
Second argument is: 2

Приклад #2 func_get_arg() example before and after PHP 5.3

test.php
<?php
function foo() {
    include 
'./fga.inc';
}

foo('First arg''Second arg');
?>

fga.inc
<?php

$arg 
func_get_arg(1);
var_export($arg);

?>

Output previous to PHP 5.3:

'Second arg'

Output in PHP 5.3 and later:

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

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

<?php
function byVal($arg) {
    echo 
'As passed     : 'var_export(func_get_arg(0)), PHP_EOL;
    
$arg 'baz';
    echo 
'After change  : 'var_export(func_get_arg(0)), PHP_EOL;
}

function 
byRef(&$arg) {
    echo 
'As passed     : 'var_export(func_get_arg(0)), PHP_EOL;
    
$arg 'baz';
    echo 
'After change  : 'var_export(func_get_arg(0)), PHP_EOL;
}

$arg 'bar';
byVal($arg);
byRef($arg);
?>

Наведений вище приклад виведе:


As passed : 'bar'
After change : 'bar'
As passed : 'bar'
After change : 'baz'

Примітки

Зауваження:

Оскільки для визначення параметрів даної функції потрібен контекст виконання, її не можна передавати як параметр функції у версіях PHP, раніших ніж 5.3.0. Якщо функцію все ж треба передати, то спочатку її необхідно призначити змінній, яку вже потім можна передавати.

Зауваження:

Якщо аргументи передаються через посилання, то будь-які зміни аргументів будуть відображені в значеннях, що повертаються цією функцією.

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

Прогляньте Також

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User Contributed Notes 5 notes

up
8
beta3designs [at] gmail [dot] com
12 years ago
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.

<?php

//Calculate the average of the numbers given

function avg(){
   
$sum = 0;
    for(
$i = 0; $i < func_num_args(); $i++){
       
$sum += func_get_arg($i);
    }
   
$avg = $sum / func_num_args();
    return
$avg;
}

echo
sprintf("%.2f",avg(2,1,2,1,3,4,5,1,3,6));
?>
up
2
gordon at abetz-rouse dot com dot au
2 years ago
This function may work differently from php5 to php7, in the latter it seems to reference the variable, while in php5 it returns the original argument.
I have confirmed with the versions below, but this will require further confirmation as to whether this is a 5 versus 7 issue.

function test( $test ){

    $test = '123';

    echo func_get_arg(0);

}

test( '321' );

//in php 5.5.9, this script will write '321'
//in php 7.0.33, this script will write '123'
up
1
mightye (at) mightye (dot) org
18 years ago
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.
up
-4
mw atto lanfear dotto com
17 years ago
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!!!):

<?php

class ABC
{
    function
__construct()
    {
        foreach (
func_get_args() as $name => $value)
        {
    echo <<<EOT
    <br/>
   
$name : $value <br/>
    <br/>

EOT;
        }
    }
}

class
DEF extends ABC
{
    function
__construct()
    {
       
parent::__construct(func_get_arg(0),
                                   
func_get_arg(1),
                                   
func_get_arg(2));
    }
}

$def = new DEF(123123, "asdfasdf", "blahblahblah");

?>

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.
up
-5
anders at ingemann dot fakestuff dot de
17 years ago
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.
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