"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"
func_get_args
(PHP 4, PHP 5)
func_get_args — 関数の引数リストを配列として返す
説明
array func_get_args ( void )関数の引数リストを配列で取得します。
この関数は func_num_args() および func_get_arg() と組み合わせて使用され、 これによりユーザ定義の章において可変長の引数リストを使用することができるようになります。
返り値
配列を返します。この配列の各要素は、 現在のユーザ定義関数の引数リストにおける対応するメンバのコピーとなります。
エラー / 例外
ユーザ定義関数の外部からコールされた際に警告を発生します。
例
例 725. func_get_args() の例
<?php
function foo()
{
$numargs = func_num_args();
echo "引数の数: $numargs<br />\n";
if ($numargs >= 2) {
echo "二番目の引数は: " . func_get_arg(1) . " です。<br />\n";
}
$arg_list = func_get_args();
for ($i = 0; $i < $numargs; $i++) {
echo "引数 $i は: " . $arg_list[$i] . " です。<br />\n";
}
}
foo(1, 2, 3);
?>
注意
注意: この関数は、 カレントスコープに依存してパラメータの詳細を決定しますので、 関数パラメータとして使用することはできません。 もし、この値を渡さなければならない場合、戻り値を変数に割り当て、 その変数を渡してください。
注意: この関数は、渡された引数のみのコピーを返します。 デフォルトの（渡されていない）引数については考慮しません。
参考
| func_get_arg() |
| func_num_args() |
func_get_args
ario [a] mail [dot] utexas [dot] edu
08-May-2007 06:50
08-May-2007 06:50
jmcguire81 [at] gmail.com
22-Mar-2007 07:13
22-Mar-2007 07:13
Here is another variation on accepting a variable number of arguments. This allows for a variable number of arguments to be passed to a Class constructor, as well as a customized class version to be used dynamically. Syntax in code is:
$mail = Generator("MailClassName", $db_ref);
function Generator() {
$numargs = func_num_args();
$classname = func_get_arg(0);
$argstring='';
if ($numargs > 1) {
$arg_list = func_get_args();
for ($x=1; $x<$numargs; $x++) {
$argstring .= '$arg_list['.$x.']';
if ($x != $numargs-1) $argstring .= ',';
}
}
if (class_exists("Custom{$classname}")) {
$classname = "Custom{$classname}";
if ($argstring) return eval("return new $classname($argstring);");
return new $classname;
}
if ($argstring) return eval("return new $classname($argstring);");
return new $classname;
}
Hope this is of use to someone.
rafagd at gmail dot com
14-Feb-2007 01:53
14-Feb-2007 01:53
Sometimes, you may need to dynamic set and get of args...
This function merge array args, so you can dynamic set some args by sending an array arg.
<?
function dynamicArgs(/*$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)
}
01-Nov-2006 03:26
Same idea as below, but this:
foreach( $args as $k => $v ){
switch($k){
case 'a':
$this->a= $v; break;
case 'b':
$this->b= $v; break;
case 'c':
$this->c= $v; break;
}
}
can be shortened to this (as long as all public variables have default values set in their declarations):
foreach( $args as $k=>$v)
if(isset($this->$k)) $this->$k = $v;
kidekat
01-Oct-2006 10:02
01-Oct-2006 10:02
To pass named arguments in a Perl fashion through class constructors, I use this:
<?php
class Test{
// set class defaults for values not assigned by constructor
public $a = 0;
public $b = 'string';
public $c = array();
public function __construct( $args = array() ) {
// parse tagged arguments in Perl fashion
foreach( $args as $k => $v ){
switch($k){
case 'a':
$this->a= $v; break;
case 'b':
$this->b= $v; break;
case 'c':
$this->c= $v; break;
}
}
}
}
$t = new Test( array( 'b'=>'new value', 'c'=>array(1,'test') ) );
?>
This allows $a to keep its default of 0, while $b gets reassigned to 'new value' and $c becomes the array(1,'test'). The catch is that you add O(n^2) "big-O notation" to the begging of every class constructor which becomes expensive on "larger" classes. While arguments defaults like the following have only O(n) "constant" amount of work.
<?php
public funciton __construct( $a=0, $b='string', $c=array()){ ... }
?>
bew
01-Apr-2006 12:55
01-Apr-2006 12:55
A more concise way of expressing my idea from the previous post (I'd forgotten about array_slice()):
<?php
function func_get_default_args($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');
?>
Nathan Ostgard
07-Dec-2005 03:14
07-Dec-2005 03:14
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.
robert at defore dot st
15-Feb-2005 05:47
15-Feb-2005 05:47
# Another attempt at named args (perl-inspired):
# list_to_assoc('key', 'value', 'key', 'value', ...) =>
# pairs[]
function list_to_assoc() {
$list = func_get_args();
$assoc = array();
while ($list and count($list) > 1) {
$assoc[array_shift($list)] = array_shift($list);
}
if ($list) { $assoc[] = $list[0]; }
return $assoc;
}
# Usage:
function example($required) {
$args = func_get_args(); array_shift($args); # drop 'required'
$rest = list_to_assoc($args);
echo "$required\n" . $rest['comment'];
}
example("This is required...",
'comment', 'this is not.'); # this is like 'comment' => 'this is not'
T.M.
05-Nov-2004 12:24
05-Nov-2004 12:24
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
?>
volte6 at drunkduck dot com
01-Oct-2004 06:54
01-Oct-2004 06:54
For those who have a use for a C style enum() function:
//*******************************************
// 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.
mark at manngo dot net
24-Mar-2003 04:13
24-Mar-2003 04:13
You can also fake named arguments using eval:
function test()
{ foreach (func_get_args() as $k=>$arg) eval ("\$$arg;");
echo "$a plus $b gives ".($a+$b);
}
test("a=3","b=4");
fbeyer at clickhand dot de dot noSpamPlease
20-Jan-2002 01:02
20-Jan-2002 01:02
Another way of passing references with a dynamic number of arguments: (This example is limited to 10 arguments)
<?php
define('NULL_ARG', 'DUMMY_ARGUMENT');
function refArg($arg0 = NULL_ARG,
$arg1 = NULL_ARG,
$arg2 = NULL_ARG,
$arg3 = NULL_ARG,
$arg4 = NULL_ARG,
$arg5 = NULL_ARG,
$arg6 = NULL_ARG,
$arg7 = NULL_ARG,
$arg8 = NULL_ARG,
$arg9 = NULL_ARG)
{
for ($args=array(), $i=0; $i < 10; $i++) {
$name = 'arg' . $i;
if ($i < func_num_args()) {
$args[$i] = &$$name;
}
unset($$name, $name);
}
$args[0] = 'Modified.';
}
$test = 'Not modified.<br>';
refArg(&$test);
echo $test; // Prints 'Modified'
?>
daveNO at ovumSPAMdesign dot com
18-Sep-2001 03:29
18-Sep-2001 03:29
<?php
// How to simulate named parameters in PHP.
// By Dave Benjamin <dave@ovumdesign.com>
// Turns the array returned by func_get_args() into an array of name/value
// pairs that can be processed by extract().
function varargs($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 = $b\n");
?>
04-Jun-2001 11:44
You can pass a variable number of arguments to a function whilst keeping references intact by using an array. The disadvantage of course, is that the called function needs to be aware that it's arguments are in an array.
<?
// Prints "hello mutated world"
function mutator($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";
?>