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
?>
func_get_args
(PHP 4, PHP 5, PHP 7, PHP 8)
func_get_args — 返回一个包含函数参数列表的数组
说明
func_get_args(): array
获取函数参数列表的数组。
该函数可以配合 func_get_arg() 和 func_num_args() 一起使用，从而使得用户自定义函数可以接受自定义个数的参数列表。
参数
此函数没有参数。
返回值
返回一个数组，其中每个元素都是目前用户自定义函数的参数列表的相应元素的副本。
错误／异常
在用户自定义函数外调用则会出现错误警告。
示例
示例 #1 func_get_args() 例子
<?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);
?>以上示例会输出：
Number of arguments: 3 Second argument is: 2 Argument 0 is: 1 Argument 1 is: 2 Argument 2 is: 3
示例 #2 byRef 和 byVal 参数的 func_get_args() 示例
<?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($arg);
?>以上示例会输出：
As passed : array (
0 => 'bar',
)
After change : array (
0 => 'baz',
)
As passed : array (
0 => 'bar',
)
After change : array (
0 => 'baz',
)
注释
注意:
As of PHP 8.0.0, the func_*() family of functions is intended to be mostly transparent with regard to named arguments, by treating the arguments as if they were all passed positionally, and missing arguments are replaced with their defaults. This function ignores the collection of unknown named variadic arguments. Unknown named arguments which are collected can only be accessed through the variadic parameter.
注意:
如果参数以引用方式传递，函数对该参数的任何改变将在函数返回后保留。As of PHP 7 the current values will also be returned if the arguments are passed by value.
注意: 该函数仅仅是返回传递参数的一个副本，并且不包含没有传入的默认参数。
参见
...语法- func_get_arg() - 返回参数列表的某一项
- func_num_args() - 返回传递给函数的参数数量
- ReflectionFunctionAbstract::getParameters() - 获取参数
add a note
User Contributed Notes 10 notes
T.M. ¶
19 years ago
cobrattila at gmail dot com ¶
4 years ago
If you want to get the arguments by reference, instead of func_get_args() you can simply use
<?php
function args_byref(&...$args) {
// Modify the $args array here
}
?>
Credits should go to Markus Malkusch for pointing this out on Stackoverflow.
https://stackoverflow.com/a/29181826/1426064
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
?>
foxkeys at gmail dot com ¶
8 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"
?>
mitko at edabg dot com ¶
15 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>
*/
?>
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 $c";
?>
OpenTechnologist ¶
12 years ago
please note that optional parameters are not seen/passed by func_get_args(), as well as func_get_arg().
ex:
<?php
function testfunc($optional = 'this argument is optional..') {
$args = func_get_args();
var_dump($args);
echo $optional;
}
?>
test case #1:
testfunc('argument no longer optional..');
result for #1:
array(1) {
[0]=> string(20) "argument no longer optional.."
}
argument no longer optional..
test case #2:
testfunc('argument no longer optional..','this is an extra argument');
result for #2:
array(2) {
[0]=> string(29) "argument no longer optional.."
[1]=> string(25) "this is an extra argument"
}
argument no longer optional..
test case #3: -- RESULTS IN AN EMPTY ARRAY
testfunc();
result for #3:
array(0) {
}
this argument is optional..
ario [a] mail [dot] utexas [dot] edu ¶
16 years ago
"Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter. If you must pass this value, assign the results to a variable, and pass the variable."
This means that the following code generates an error:
<?php
function foo($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"
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");
?>
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'];
}
?>
