PHP Manual: Return an item from the argument list

Description

mixed func_get_arg(int $position)

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

position: 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 position 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 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);
?>

The above example will output:

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

Notes

Note:
As of PHP 8.0.0, the func_*() family of functions is intended to be mostly transparent with regard to named arguments, by treating the arguments as if they were all passed positionally, and missing arguments are replaced with their defaults. This function ignores the collection of unknown named variadic arguments. Unknown named arguments which are collected can only be accessed through the variadic parameter.

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