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function_exists> <func_get_args
[edit] Last updated: Sat, 12 May 2012

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func_num_args

(PHP 4, PHP 5)

func_num_argsReturns the number of arguments passed to the function

Description

int func_num_args ( void )

Gets the number of arguments passed to the function.

This function may be used in conjunction with func_get_arg() and func_get_args() to allow user-defined functions to accept variable-length argument lists.

Return Values

Returns the number of arguments passed into the current user-defined function.

Changelog

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 -1.

Errors/Exceptions

Generates a warning if called from outside of a user-defined function.

Examples

Example #1 func_num_args() example

<?php
function foo()
{
    
$numargs func_num_args();
    echo 
"Number of arguments: $numargs\n";
}

foo(123);   
?>

The above example will output:

Number of arguments: 3

Example #2 func_num_args() example before and after PHP 5.3

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

foo('First arg''Second arg');
?>

fna.php
<?php

$num_args 
func_num_args();
var_export($num_args);

?>

Output previous to PHP 5.3:

2

Output in PHP 5.3 and later will be something similar to:

Warning: func_num_args():  Called from the global scope - no function
context in /home/torben/Desktop/code/ml/fna.php on line 3
-1

Notes

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.

See Also



function_exists> <func_get_args
[edit] Last updated: Sat, 12 May 2012
 
add a note add a note User Contributed Notes func_num_args
luisguillermo dot quevedovelez at gmail dot com 13-Mar-2012 07:32
I had defined a function function_name(){ ...} as a drupal callback.
I try to get how many params where passed

I got a Error and my Site falls down

I've replaced func_get_args() instead func_num_args() and my Site was restored.

I conclude you can not use  func_num_args() in callbacks.

Hope it helps.
Dennis Robinson from basnetworks dot net 29-Jun-2009 09:29
This function comes in handy, and I believe is the only solution, when you have an optional parameter that can take any type of data.

For example:

<?php

// $data can be of any type, including null
function my_function($name, $data = null)
{
    if (
$data !== null)
    {
       
// Do something with $data
        // If you call my_function('something'), this WILL NOT be reached
        // If you call my_function('something', null), this WILL NOT be reached
   
}
}

?>

The problem with the above function is that you will never be able to use null as the value for $data.  To fix this, use func_num_args() like so:

<?php

// $data can be of any type, including null
function my_function($name, $data = null)
{
    if (
func_num_args() >= 2)
    {
       
// Do something with $data
        // If you call my_function('something'), this WILL NOT be reached
        // If you call my_function('something', null), this WILL be reached
   
}
}

?>

This solution works because func_num_args() reports exactly how many arguments were passed when the function was called.  It does not take into account when default argument values are used.
padron at aaargh dot com dot br 19-Jan-2007 11:18
func_num_args(), func_get_args() and func_get_arg() can be very useful to emulate overloading in PHP.

Suppose you have a class to add a user in a system, and that you want to allow 2 ways of doing it. The first way would be passing an array with all the user info in it, and the second way would be passing each user attribute as a single argument.

<?php

class Test {

    function
insertUser() {

       
// gets the number of parameters
       
$numArgs = func_num_args();
       
       
// make decisions based on the arguments number
       
if ($numArgs == 1) {
           
// if it's only one argument, we suppose that it is an array with user info
           
            // gets the first argument
           
$user = func_get_arg(0);
           
           
// checks if it really is an array
           
if (is_array($user)) {
               
               
// here you should check if the array contains all necessary fields
               
                // adds the user
               
echo "User added.<br/>";
                echo
"ID: " . $user["id"] . "<br/>";
                echo
"NAME: " . $user["name"] . "<br/>";
                echo
"EMAIL: " . $user["email"] . "<br/>";
               
            } else {
               
               
// generates an error if argument is not an array
               
echo "Argument is not an array: " . $user . ".<br/>";
               
            }
           
        } else if (
$numArgs == 3) {
           
// if the function receives 3 arguments, we assume that they
            // are 'id', 'name' and 'email' respectively
           
            // inserts the user into the system
           
echo "User added.<br/>";
            echo
"ID: " . func_get_arg(0) . "<br/>";
            echo
"NAME: " . func_get_arg(1) . "<br/>";
            echo
"EMAIL: " . func_get_arg(2) . "<br/>";
                       
        } else {
           
           
// if the number of arguments is different from 1 and 3
            // an error will be generated
           
           
echo "Wrong argument number.<br/>";
            echo
"Arguments received: " . func_num_args();
           
        }
    }

}

// creates an Test object
$objTest = new Teste();

// inserts an user passing an array with all his info
$objTest->insertUser(array("id" => 1, "name" => "George W. Bush", "email" => "jackass@whitehouse.gov"));

echo
"<br/>";

// inserts an user providing each attribute as a single argument
$objTest->insertUser(2, "Vicente Fox", "iloveusa@disney.com");

echo
"<br/>";

// this will generate an error, because only 2 arguments were passed
$objTest->insertUser(3, "Tony Blair");

?>
neelam_ab2003 at yahoo dot co dot in 11-May-2006 12:40
Just adding a note to JARED's Note.

func_num_args() works if and only if called from within a function definition BECAUSE it calculates the number of arguments sent while function calling. That is why it gives

'1' in helloWorld("HelloWorld!") and '2' in helloWorld("HelloWorld!", "HowdyWorld!") - There is nothing to do with DEFAULT args.

If you call the same function as helloWorld(); "No args passed"

It will give a warning for wrong function call ("Warning: Missing argument 1 for helloWorld()") and the result of func_num_args() will be '0'.
friz at godshell dot com 16-Mar-2006 11:24
This function comes in extremely handy in OO Classes.  My focus is currently PHP 4, but this technique probably works just as well in PHP 5.

<?php
Class foo {
  
// constructor, other methods, etc

  
function somedata($somedata = '') {
      if (
func_num_args() > 0) {
        
$this->somedata = $somedata;
      }

      return
$this->somedata;
   }
}
?>

This allows for a default value to be set, while not requiring the parameter.  (Yes, I'm aware that it only warns when you do, but I think this is a little cleaner)
jared at ws-db dot com 06-Sep-2005 09:46
Just a note for anyone wondering. This function doesn't include params that have a default value, unless you pass one in to overwrite the default param value. Not sure if that makes sense, so here's an example:

<?php
function helloWorld($ArgA, $ArgB="HelloWorld!") {
  return
func_num_args();
}

// The following will return 1
$Returns1 = helloWorld("HelloWorld!");

// The following will return 2
$Returns2 = helloWorld("HelloWorld!", "HowdyWorld!");
?>
andy at arakka dot co dot th 11-May-2005 07:16
func_num_args() can be used in conjunction with named arguments, also. For example:

<?php
function DebugShow( $label, $value ) {
  echo
"# " . $label ;
  if (
func_num_args() > 1 ) echo " = " . $value ;
  echo
"<br>";
}
?>
ashley at dcs dot warwick dot ac dot uk 17-Apr-2002 04:40
If you want to pass the parameters on intact to another function, use func_get_args and call_user_func_array (careful - this one is only available in recent PHP versions).  For example:

<?php
/* Print an HTML tag.  This accepts a variable number of arguments:
   the first should be the name of the tag, followed by pairs of
   arguments that describe keys and values.  The values are printed
   with surrounding double quote characters.  */
function printTag() {
 
$numArgs = func_num_args();
  if (
$numArgs < 1) die("printTag given no arguments");
 
  echo
"<" . func_get_arg(0);
  for (
$i = 1; $i < $numArgs; $i+=2) {
    echo
" " . func_get_arg($i);
    if (
$i+1 < $numArgs)
      echo
"=\"" . func_get_arg($i+1) . "\"";
  }
  echo
">";
 
}

/* Print an HTML tag with a newline on the end */
function printTagNL() {
 
$args = func_get_args();
 
call_user_func_array("printTag", $args);
  echo
"\n";
}

printTagNL("input", "type", "hidden", "name", "SORTORDER", "value", $columnNo);
?>
thalis at NOSPAMcs dot pitt dot edu 29-Mar-2002 12:05
The idea of func_get_args() is to construct functions of variable number of parameters like

<?php
function var_param_func(){
    if(
func_num_args()==0){
       
//do one thing
   
}
    if(
func_num_args()==1)
       
//do another thing
        //get the args with func_get_args()
   
}
}
?>

 
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