PHP Unconference Europe 2015

func_get_args

(PHP 4, PHP 5)

func_get_argsDevuelve un array que se compone de una lista de argumentos de función

Descripción

array func_get_args ( void )

Obtiene un array de la lista de argumentos de una función.

Esta función se puede usar junto con func_get_arg() y func_num_args() para permitir a las funciones definidas por el usuario aceptar una lista de argumentos de longitud variable.

Valores devueltos

Devuelve un array en el que cada elemento es una copia del miembro correspondiente de la lista de argumentos de la función definida por el usuario.

Historial de cambios

Versión Descripción
5.3.0 Esta función ahora se puede usar en listas de parámetros.
5.3.0 Si esta función es llamada desde el ámbito último de un archivo que ha sido incluido mediante una llamada a include o require desde dentro de una función en el archivo de llamada, ahora genera una advertencia y devuelve FALSE.

Errores/Excepciones

Genera una advertencia si se llama desde fuera de una función definida por el usuario.

Ejemplos

Ejemplo #1 Ejemplo de func_get_args()

<?php
function foo()
{
    
$númargs func_num_args();
    echo 
"Número de argumentos: $númargs<br />\n";
    if (
$númargs >= 2) {
        echo 
"El segundo argumento es: " func_get_arg(1) . "<br />\n";
    }
    
$arg_list func_get_args();
    for (
$i 0$i $númargs$i++) {
        echo 
"El argumento $i es: " $arg_list[$i] . "<br />\n";
    }
}

foo(123);
?>

El resultado del ejemplo sería:

Número de argumentos: 3<br />
El segundo argumento es: 2<br />
El argumento 0 es: 1<br />
El argumento 1 es: 2<br />
El argumento 2 es: 3<br />

Ejemplo #2 Ejemplo de func_get_args() antes y después de PHP 5.3

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

foo('Primer argumento''Segundo argumento');
?>

fga.inc
<?php

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

?>

Salida antes de PHP 5.3:

array (
  0 => 'Primer argumento',
  1 => 'Segundo argumento',
)

Salida en PHP 5.3 y posterior:

Warning: func_get_args():  Called from the global scope - no function
context in /home/torben/Desktop/code/ml/fga.inc on line 3
false

Ejemplo #3 func_get_args() ejemplo de argumentos byref (pasa un objeto como referencia) y byval (pasa un objeto como valor)

<?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);
?>

El resultado del ejemplo sería:


Pasó como : array (
0 => 'bar',
)
Tras el cambio : array (
0 => 'bar',
)
Pasó como : array (
0 => 'bar',
)
Tras el cambio : array (
0 => 'baz',
)

Notas

Nota:

Como esta función depende del ámbito actual para determinar los detalles del parámetro, no puede ser usada como parámetro de función en versiones anteriores a 5.3.0. Si se require pasar el valor, los resultados deben ser asignados a una variable y esta variable debería pasarse como parámetro.

Nota:

Si los argumentos se pasan por su referencia, cualquier cambio en ellos será reflejado en los valores devueltos por esta función.

Nota: Esta función solamente devuelve una copia de los argumentos pasados, y no rinde cuentas de los argumentos predeterminados (no pasados).

add a note add a note

User Contributed Notes 21 notes

up
8
anderson at francotecnologia dot com
6 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
5
maarten at ba dot be
2 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
4
T.M.
9 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
3
Sinured
7 years ago
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.
up
1
Nathan Ostgard
8 years ago
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.
up
1
Anonymous
6 years ago
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);

?>
up
1
red
3 years ago
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']);

?>
up
1
daveNO at ovumSPAMdesign dot com
13 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
OpenTechnologist
2 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
0
pBakhuis at Gmail dot com
3 years ago
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.
up
0
mulllhausen
3 years ago
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]
?>
up
0
Oto Brglez
5 years ago
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

?>
up
0
tristan dot colombo at laposte dot net
7 years ago
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();

?>
up
0
ario [a] mail [dot] utexas [dot] edu
7 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
bew
8 years ago
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');
?>
up
0
volte6 at drunkduck dot com
10 years ago
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.
up
0
Anonymous
13 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";
?>
up
-1
dev at mp3addict dot pw
7 months ago
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});");
    }
}
up
-1
mitko at edabg dot com
5 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
-1
kangaroo232002 at yahoo dot co dot uk
6 years ago
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'
?>
up
-1
rafagd at gmail dot com
7 years ago
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)
}
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