func_get_args

(PHP 4, PHP 5, PHP 7, PHP 8)

func_get_argsReturns an array comprising a function's argument list

Description

func_get_args(): array

Gets an array of the function's argument list.

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

Parameters

This function has no parameters.

Return Values

Returns an array in which each element is a copy of the corresponding member of the current user-defined function's argument list.

Errors/Exceptions

Generates a warning if called from outside of a user-defined function.

Examples

Example #1 func_get_args() 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";
}
$arg_list = func_get_args();
for (
$i = 0; $i < $numargs; $i++) {
echo
"Argument $i is: " . $arg_list[$i] . "\n";
}
}

foo(1, 2, 3);
?>

The above example will output:

Number of arguments: 3 
Second argument is: 2
Argument 0 is: 1
Argument 1 is: 2
Argument 2 is: 3

Example #2 func_get_args() example of byref and byval arguments

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

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

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

The above example will output:


As passed : array (
0 => 'bar',
)
After change : array (
0 => 'baz',
)
As passed : array (
0 => 'bar',
)
After change : array (
0 => '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.

See Also

add a note

User Contributed Notes 12 notes

up
65
T.M.
19 years ago
Simple function to calculate average value using dynamic arguments:
<?php
function average(){
return
array_sum(func_get_args())/func_num_args();
}
print
average(10, 15, 20, 25); // 17.5
?>
up
10
cobrattila at gmail dot com
4 years ago
If you want to get the arguments by reference, instead of func_get_args() you can simply use

<?php
function args_byref(&...$args) {
// Modify the $args array here
}
?>

Credits should go to Markus Malkusch for pointing this out on Stackoverflow.
https://stackoverflow.com/a/29181826/1426064
up
16
anderson at francotecnologia dot com
15 years ago
How to create a polymorphic/"overloaded" function

<?php
function select()
{
$t = '';
$args = func_get_args();
foreach (
$args as &$a) {
$t .= gettype($a) . '|';
$a = mysql_real_escape_string($a);
}
if (
$t != '') {
$t = substr($t, 0, - 1);
}
$sql = '';
switch (
$t) {
case
'integer':
// search by ID
$sql = "id = {$args[0]}";
break;
case
'string':
// search by name
$sql = "name LIKE '%{$args[0]}%'";
break;
case
'string|integer':
// search by name AND status
$sql = "name LIKE '%{$args[0]}%' AND status = {$args[1]}";
break;
case
'string|integer|integer':
// search by name with limit
$sql = "name LIKE '%{$args[0]}%' LIMIT {$args[1]},{$args[2]}";
break;
default:
// :P
$sql = '1 = 2';
}
return
mysql_query('SELECT * FROM table WHERE ' . $sql);
}
$res = select(29); // by ID
$res = select('Anderson'); // by name
$res = select('Anderson', 1); // by name and status
$res = select('Anderson', 0, 5); // by name with limit
?>
up
3
foxkeys at gmail dot com
7 years ago
Merge func_get_args() with function defaults
<?php
class utils {
/**
* @param mixed[] $args
* @param ReflectionMethod $reflectionMethod
*
* @return array
*/
public static function mergeArgsWithDefaults( $args, \ReflectionMethod $reflectionMethod ) {
foreach (
array_slice( $reflectionMethod->getParameters(), count( $args ) ) as $param ) {
/**
* @var ReflectionParameter $param
*/
$args[] = $param->getDefaultValue();
}
return
$args;
}
}

class
sampleParent {
const
USER_FILE_TYPE_FILE = 'FILE';
public function
select( $idUserFile = null, $idUserFileType = self::USER_FILE_TYPE_FILE ) {
echo
'[$idUserFile=>' . $idUserFile . ', $idUserFileType=>' . $idUserFileType, ']<br/>' . PHP_EOL;
}
}

class
sample extends sampleParent {
const
USER_FILE_TYPE_IMG = 'IMG';
public function
select( $idUserFile = null, $idUserFileType = self::USER_FILE_TYPE_IMG ) {
return
call_user_func_array( 'parent::select', \utils::mergeArgsWithDefaults( func_get_args(), new ReflectionMethod( __CLASS__, __FUNCTION__ ) ) );
}
}

$sample1 = new sampleParent();
$sample1->select();//Prints "" / self::USER_FILE_TYPE_FILE
$sample1->select(1);//Prints 1 / self::USER_FILE_TYPE_FILE
$sample1->select(2, 'test 1');//Prints 2 / "test 1"
echo '<br/>' . PHP_EOL;
$sample2 = new sample();
$sample2->select();//Prints "" / self::USER_FILE_TYPE_IMG
$sample2->select(3);//Prints 3 / self::USER_FILE_TYPE_IMG
$sample2->select(4, 'test 2');//Prints 4 / "test 2"
?>
up
4
OpenTechnologist
12 years ago
please note that optional parameters are not seen/passed by func_get_args(), as well as func_get_arg().

ex:

<?php
function testfunc($optional = 'this argument is optional..') {
$args = func_get_args();
var_dump($args);
echo
$optional;
}
?>

test case #1:
testfunc('argument no longer optional..');

result for #1:
array(1) {
[0]=> string(20) "argument no longer optional.."
}
argument no longer optional..

test case #2:
testfunc('argument no longer optional..','this is an extra argument');

result for #2:
array(2) {
[0]=> string(29) "argument no longer optional.."
[1]=> string(25) "this is an extra argument"
}
argument no longer optional..

test case #3: -- RESULTS IN AN EMPTY ARRAY
testfunc();

result for #3:
array(0) {
}
this argument is optional..
up
1
daveNO at ovumSPAMdesign dot com
22 years ago
<?php
// How to simulate named parameters in PHP.
// By Dave Benjamin <dave@ovumdesign.com>

// Turns the array returned by func_get_args() into an array of name/value
// pairs that can be processed by extract().
function varargs($args) {
$count = count($args);
for (
$i = 0; $i < $count; $i += 2) {
$result[$args[$i]] = $args[$i + 1];
}

return
$result;
}

// Example
function test(&$ref1, &$ref2) {
// Default arguments go here.
$foo = "oof";

// Do some magic.
extract(varargs(func_get_args()));

echo
nl2br("\n\$var1 = $var1");
echo
nl2br("\n\$var2 = $var2");
echo
nl2br("\n\$foo = $foo\n\n");

// Modify some variables that were passed by reference.
// Note that func_get_args() doesn't pass references, so they
// need to be explicitly declared in the function definition.
$ref1 = 42;
$ref2 = 84;
}

$a = 5;
$b = 6;

echo
nl2br("Before calling test(): \$a = $a\n");
echo
nl2br("Before calling test(): \$b = $b\n");

// Try removing the 'foo, "bar"' from the following line.
test($a, $b, var1, "abc", var2, "def", foo, "bar");

echo
nl2br("After calling test(): \$a = $a\n");
echo
nl2br("After calling test(): \$b = $b\n");
?>
up
0
hans at loltek dot net
4 months ago
I wanted an associative list of arguments, in case some else does too, I'm leaving it here.

I hope PHP gets native support for this, because a core implementation would be faster than this userland backtrace+reflection implementation:
<?php

/**
* Get function arguments as associative array
* (same as func_get_args() but with keys)
*
* @param bool $populateMissingArgumentsWithDefaults whether to populate the array with default values for missing arguments
*
* @return array
*/
function func_get_args_associative(bool $populateMissingArgumentsWithDefaults = false): array
{
$trace = debug_backtrace(0, 2)[1];
$reflection = null;
if (isset(
$trace['class'])) {
$reflection = new \ReflectionMethod($trace['class'], $trace['function']);
} else {
$reflection = new \ReflectionFunction($trace['function']);
}
$ret = [];
foreach (
$reflection->getParameters() as $param) {
if (
array_key_exists($param->getPosition(), $trace['args'])) {
$ret[$param->name] = $trace['args'][$param->getPosition()];
} elseif (
$populateMissingArgumentsWithDefaults) {
// because of the "required arguments declared after an optional argument are implicitly required" rule:
assert($param->isDefaultValueAvailable(), "i think all params are either in trace[args] or have default values");
$ret[$param->name] = $param->getDefaultValue();
}
}
return
$ret;
}
?>
up
0
art at geigel dot com
11 months ago
The size of the array resulting from func_get_args(), for instance using count(), does not take into account parameters that have been assigned default values in the function definition.

Example:

function foo($bar=true) {
echo count(func_get_args());
}

foo();
// echoes 0

foo("bar");
// echoes 1

A useful condition to test for when a function needs to return default behavior (whatever that might be) when no value is present and the value of $bar could be true, false, null, etc.
up
0
maarten at ba dot be
11 years ago
it seems that this function only returns a copy and loses it's byref information, use this dirty non-efficient workaround instead:

at the moment of writing it currently returns all of them as references, instead of only the ones who are passed that way...

<?php
function func_get_args_byref() {
$trace = debug_backtrace();
return
$trace[1]['args'];
}
?>
up
0
mitko at edabg dot com
14 years ago
<?php
/*
This example demonstrate how to use unknown variable arguments by reference.
func_get_args() don't return arguments by reference, but
debug_backtrace() "args" is by reference.
In PHP 5 this have no particular sense, because calling with arguments by reference
is depreciated and produce warning.
*/

class foo {

var
$bar = "default bar";

function
foo(/*variable arguments*/) {
// func_get_args returns copy of arguments
// $args = func_get_args();
// debug_backtrace returns arguments by reference
$stack = debug_backtrace();
$args = array();
if (isset(
$stack[0]["args"]))
for(
$i=0; $i < count($stack[0]["args"]); $i++)
$args[$i] = & $stack[0]["args"][$i];
call_user_func_array(array(&$this, 'bar'), $args);
}


function
bar($bar = NULL) {
if (isset(
$bar))
$this->bar = & $bar;
}
}

$global_bar = "bar global";
$foo = & new foo();
echo
"foo->bar: ".$foo->bar."</br>\n";
$foo->bar = "new bar";
echo
"global_bar: ".$global_bar."</br>\n";
/*
Result:
foo->bar: default bar</br>
global_bar: bar global</br>
*/

$foo = & new foo(&$global_bar);
echo
"foo->bar: ".$foo->bar."</br>\n";
$foo->bar = "new bar";
echo
"global_bar: ".$global_bar."</br>\n";
/*
Result:
foo->bar: bar global</br>
global_bar: new bar</br>
*/

?>
up
0
ario [a] mail [dot] utexas [dot] edu
16 years ago
"Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter. If you must pass this value, assign the results to a variable, and pass the variable."

This means that the following code generates an error:

<?php

function foo($list)
{
echo
implode(', ', $list);
}

function
foo2()
{
foo(func_get_args());
}

foo2(1, 2, 3);

?>

However, you can easily get around this by doing the following:

<?php

function foo($list)
{
echo
implode(', ', $list);
}

function
foo2()
{
foo($args = func_get_args());
}

foo2(1, 2, 3);

?>

This captures the context from foo2(), making this legal. You get the expected output:

"1, 2, 3"
up
0
Anonymous
22 years ago
You can pass a variable number of arguments to a function whilst keeping references intact by using an array. The disadvantage of course, is that the called function needs to be aware that it's arguments are in an array.

<?php
// Prints "hello mutated world"
function mutator($args=null) {
$n=count($args);
while(
$i<$n) $args[$i++] = "mutated";
}
$a = "hello";
$b = "strange";
$c = "world";
mutator(array($a, &$b, $c));
echo
"$a $b $c";
?>
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