PHP 7.0.6 Released

func_num_args

(PHP 4, PHP 5, PHP 7)

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.

User Contributed Notes

jared at ws-db dot com
10 years ago
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!");
?>
Dennis Robinson from basnetworks dot net
6 years ago
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.
ashley at dcs dot warwick dot ac dot uk
14 years ago
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);
?>
luisguillermo dot quevedovelez at gmail dot com
4 years ago
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.
thalis at NOSPAMcs dot pitt dot edu
14 years ago
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()
   
}
}
?>
andy at arakka dot co dot th
10 years ago
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>";
}
?>
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