PHP Manual: Return an item from the argument list

Description

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.

Parameters

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

Return Values

Returns the specified argument, or FALSE on error.

Changelog

Version	Description
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`.

Errors/Exceptions

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.

Examples

Example #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(1, 2, 3);
?>

The above example will output:

Number of arguments: 3
Second argument is: 2

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.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

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);
?>

Output of the above example in PHP 7:

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

Output of the above example in PHP 5:

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

Notes

Note:
Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter in versions prior to 5.3.0. If this value must be passed, the results should be assigned to a variable, and that variable should be passed.

Note:
If the arguments are passed by reference, any changes to the arguments will be reflected in the values returned by this function. As of PHP 7 the current values will also be returned if the arguments are passed by value.

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

func_get_arg