func_get_arg Return an item from the argument list php函数


func_get_arg

(PHP 4, PHP 5)

func_get_argReturn an item from the argument list

说明

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.

参数

arg_num

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

返回值

Returns the specified argument, or FALSE on error.

更新日志

版本 说明
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.

错误/异常

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.

范例

Example #1 func_get_arg() example

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

foo (123);
?>

Example #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.php
<?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

Example #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);
?>

以上例程会输出:


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

注释

Note:

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:

If the arguments are passed by reference, any changes to the arguments will be reflected in the values returned by this function.

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() - Returns an array comprising a function's argument list
  • func_num_args() - Returns the number of arguments passed to the function



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