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
?>
(PHP 4, PHP 5, PHP 7)
func_get_args — Returns an array comprising a function's argument list
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.
Returns an array in which each element is a copy of the corresponding member of the current user-defined function's argument list.
| 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.
|
Generates a warning if called from outside of a user-defined function.
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 before and after PHP 5.3
test.php
<?php
function foo() {
include './fga.inc';
}
foo('First arg', 'Second arg');
?>
fga.inc
<?php
$args = func_get_args();
var_export($args);
?>
Output previous to PHP 5.3:
array ( 0 => 'First arg', 1 => 'Second arg', )
Output in PHP 5.3 and later:
Warning: func_get_args(): Called from the global scope - no function context in /home/torben/Desktop/code/ml/fga.inc on line 3 false
Example #3 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);
?>
Output of the above example in PHP 7:
Output of the above example in PHP 5:
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.
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
?>
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
$res = select('Anderson', 0, 5); // by name with limit
?>
It may seem obvious, but if you want your variadic function to at least require one parameter, you can do this instead of checking func_num_args() == 0, which I've seen often:
<?php
function variadic($dummy) {
$args = func_get_args();
foreach ($args as $arg) {
echo "$arg<br />\n";
}
}
?>
func_get_args() fetches ALL passed parameters, not only those that weren't copied to a local variable.
I had to pass variable length arguments from one function to another. It seems the only way of doing this is to use call_user_func_array.
<?php
function query(/*query [, $arg1...$argN]*/){
$query = call_user_func_array('replaceAndClean', func_get_args());
$result = mysql_query($query);
return $result;
}
function replaceAndClean(/*query [, $arg1...$argN]*/){
$args = func_get_args();
if(count($args) == 1){
return $args[0];
}
$query = array_shift($args);
return vsprintf($query, array_map('mysql_real_escape_string', $args));
}
?>
Example:
<?php
// unsave call
query("SELECT FROM foo where bar='".$_POST['bar']."'");
// save call
query("SELECT FROM foo where bar='%d'", $_POST['bar']);
?>
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 $trace[1]['args'];
}
?>
<?php
// How to simulate named parameters in PHP.
// By Dave Benjamin <dave@ovumdesign.com>
// Turns the array returned by func_get_args() into an array of name/value
// pairs that can be processed by extract().
function varargs($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 = $b\n");
?>
I use the following concept for quick "plugin" of multiple argument support.
<?php
function increment($n) {
$p = func_get_args();
if (count($p) > 1) {
return array_map(__FUNCTION__, $p);
}
$n =& $p[0];
return ++$n;
}
list($two, $three, $four) = increment(1,2,3);
?>
please note that optional parameters are not seen/passed by func_get_args(), as well as func_get_arg().
ex:
<?php
function testfunc($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..
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
$sample2->select(4, 'test 2');//Prints 4 / "test 2"
?>
Please note that you can't use this for recursive functions as you can't pass the parameters to the function again as then they'll be in the form of an array.
i use this structure a lot for debugging. i always place the call to 'debugfunc' at the start of any function which i want to debug. the square brackets in the echod output are useful to see if there is accidental whitespace within string variables passed to anyfunc. if anyone can suggest a better way of passing the names of the arguments to debugfunc i would appreciate it. as it is works fine, but its not very universal...
<?php
anyfunc('val1','val2','val3');
function anyfunc($arg1, $arg2, $arg3)
{
debugfunc(__FUNCTION__, '$arg1, $arg2, $arg3', func_get_args());
/*do useful non-debugging stuff*/
}
function debugfunc($name, $arg_names, $arg_vals)
{
echo "begin function [$name]. ";
$arg_names_array = explode(',', $arg_names);
foreach($arg_names_array as $k => $v)
{
$v = trim($v);
echo "$v: [$arg_vals[$k]] ";
}
echo "\n";
}
//output:
//begin function [anyfunc]. $arg1: [val1] $arg2: [val2] $arg3: [val3]
?>
<?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>
*/
?>
In order to use the function 'func_get_args()' to instanciate differents type of objects, you must use the Reflection API.
By example, we have two different classes and we want to have an unique function (using an unfixed number of parameters) to create the objects. We create two classes 'a' and 'b' where constructors accept different numbers of arguments.
Class a (class/a.class.php):
<?php
include_once 'a.class.php';
class b extends a
{
private $param3;
public function __construct($a, $b, $c)
{
$this->param1 = $a;
$this->param2 = $b;
$this->param3 = $c;
}
public function display()
{
echo $this->param1 . ', ' . $this->param2 . ' and ' . $this->param3 . '!<br />';
}
}
?>
Class b (class/b.class.php):
<?php
class a
{
private $param1;
private $param2;
public function __construct($a, $b)
{
$this->param1 = $a;
$this->param2 = $b;
}
public function display()
{
echo $this->param1 . ' and ' . $this->param2 . '<br />';
}
}
?>
Main program :
<?php
function classFactory()
{
// Retrieve arguments list
$_args = func_get_args();
// Delete the first argument which is the class name
$_className = array_shift($_args);
// Include the requested class
include_once 'class/' . $_className . '.class.php';
// Create Reflection object
// See : http://www.php.net/manual/en/language.oop5.reflection.php
$_reflection = new ReflectionClass($_className);
// Use the Reflection API
return $_reflection->newInstanceArgs($_args);
}
$a = classFactory('a', 'hello', 'world');
$b = classFactory('b', 'that\'s', 'all', 'folks');
$a->display();
$b->display();
?>
"Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter. If you must pass this value, assign the results to a variable, and pass the variable."
This means that the following code generates an error:
<?php
function foo($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"
A more concise way of expressing my idea from the previous post (I'd forgotten about array_slice()):
<?php
function func_get_default_args($a) {
$args = array_slice(func_get_args(), 1);
return array_merge($args, array_slice($a, sizeof($args)));
}
function foo($a = 1, $b = 2, $c = 3) {
print_r(func_get_default_args(func_get_args(), $a, $b, $c));
}
// prints: Array ( [0] => a [1] => b [2] => 3 )
foo('a', 'b');
?>
For those who have a use for a C style enum() function:
<?php
//*******************************************
// void enum();
// enumerates constants for unique values guarenteed.
function enum()
{
$i=0;
$ARG_ARR = func_get_args();
if (is_array($ARG_ARR))
{
foreach ($ARG_ARR as $CONSTANT)
{
define ($CONSTANT, ++$i);
}
}
}
// USAGE:
enum(ERR_USER_EXISTS, ERR_OLD_POST);
// etc. etc.
//*******************************************
?>
this can be used for error codes etc.
I deliberately skipped the 0 (zero) define, which could be useful for error checking.
You can pass a variable number of arguments to a function whilst keeping references intact by using an array. The disadvantage of course, is that the called function needs to be aware that it's arguments are in an array.
<?php
// Prints "hello mutated world"
function mutator($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 $c";
?>
This function is as printf() but only calls printf() when the debug_enabled global variable is set to TRUE. Because by this way, you can use debug() instead of echo | printf() and set debug_enabled to false after checking and submitting work into production.
cheers;
function debug () {
if ($GLOBALS['debug_enabled'] == true) {
$args = func_get_args();
$fmt = $args[0];
$printf_args = '';
for ($i = 1; $i < count($args); $i++) {
$printf_args .= ",\"{$args[$i]}\"";
}
eval("printf(\"{$fmt}\"{$printf_args});");
}
}
How to create simple sum function that can sum N arguments. Like this:
<?php
function sum(){
$s=0;
foreach(func_get_args() as $a) $s+= is_numeric($a)?$a:0;
return $s;
};
print sum(1,2,3,4,5,6); // will return 21
print sum(3,2,1); // will return 6
print sum(false,array(),5,5); // will return 10
?>
Instead of having to define your arg list twice, and keeping to the good style of initialising your variables in the head of your class, you can use (PHP5):
<?php
class myclass {
public $value = null;
public $key = null;
public $column = null;
public $table = null;
public function __construct() {
$vars = get_class_vars();
for($i=0; $i<func_num_args();$i++) {
$this->${$vars[$i]}=func_get_arg($i);
}
}
}
?>
which should allow you to set variables while retaining their default values if they are not set (in this case, null), without having to mess around with functions to retain default values so is much neater (just don't change the order you declare your vars!)
<?php
//usage
$c = new myclass("value", "tablekey", "tablecol", "table");
echo $c->key;
//prints 'tablekey'
?>
If you're using PHP5, the variable number of argument functions all return the objects by reference - and not a copy of the object, as this leads you to believe.
Sometimes, you may need to dynamic set and get of args...
This function merge array args, so you can dynamic set some args by sending an array arg.
<?php
function dynamicArgs(/*$arg1, $arg2...$argN*/) {
$args = func_get_args(); $num = func_num_args();
for ($i = 1; $i < $num; $i++) {
$args[0] = array_merge((array) $args[0], (array) $args[$i]);
}
return $args[0];
}
var_dump(dynamicArgs('a',array('b','c'),'d',1);
?>
This should output like:
array(5) {
[0]=>
string(1) "a"
[1]=>
string(1) "b"
[2]=>
string(1) "c"
[3]=>
string(1) "d"
[4]=>
int(1)
}