func_get_arg

(PHP 4, PHP 5, PHP 7)

func_get_arg — Return an item from the argument list

Description

func_get_arg ( int $arg_num ) : mixed

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.

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.