php教程

func_get_args

(PHP 4, PHP 5, PHP 7)

func_get_args返回一个包含函数参数列表的数组

说明

func_get_args ( void ) : array

获取函数参数列表的数组。

该函数可以配合 func_get_arg()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。

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。

更新日志

版本 说明
5.3.0 该函数可以在参数列表中使用。
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. (不知道如何翻译跟好,直接参考例2即可明白)

错误/异常

在用户自定义函数外调用则会出现错误警告。

范例

Example #1 func_get_args() 例子

<?php
function foo()
{
    
$numargs func_num_args();
    echo 
"Number of arguments: $numargs<br />\n";
    if (
$numargs >= 2) {
        echo 
"Second argument is: " func_get_arg(1) . "<br />\n";
    }
    
$arg_list func_get_args();
    for (
$i 0$i $numargs$i++) {
        echo 
"Argument $i is: " $arg_list[$i] . "<br />\n";
    }
}

foo(123);
?>

以上例程会输出:

Number of arguments: 3<br />
Second argument is: 2<br />
Argument 0 is: 1<br />
Argument 1 is: 2<br />
Argument 2 is: 3<br />

Example #2 PHP 5.3 前后使用 func_get_args() 在的对比

test.php
<?php
function foo() {
    include 
'./fga.inc';
}

foo('First arg''Second arg');
?>

fga.inc
<?php

$args 
func_get_args();
var_export($args);

?>

PHP 5.3 版本之前的输出:

array (
  0 => 'First arg',
  1 => 'Second arg',
)

PHP 5.3 和之后的版本的输出:

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);
?>

以上例程会输出:


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

注释

Note:

因为函数依赖于当前作用域以确定参数的细节,所以在 5.3.0 以前的版本中不能用作函数的参数。如必须传递此值时,可将结果赋与一个变量,然后用此变量进行传递。

Note:

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。

Note: 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

User Contributed Notes

foxkeys at gmail dot com 17-Mar-2016 06:18
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"
?>
maarten at ba dot be 13-Sep-2012 11:58
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'];
}
?>
OpenTechnologist 30-Dec-2011 07:54
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..
mitko at edabg dot com 06-Apr-2009 03:48
<?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>
*/

?>
anderson at francotecnologia dot com 26-Aug-2008 11:25
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
?>
ario [a] mail [dot] utexas [dot] edu 07-May-2007 02:50
"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"
T.M. 04-Nov-2004 07:24
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
?>
daveNO at ovumSPAMdesign dot com 17-Sep-2001 11:29
<?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");
?>
04-Jun-2001 07:44
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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