PHP 5.4.33 Released

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.

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User Contributed Notes 6 notes

up
9
jared at ws-db dot com
9 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!");
?>
up
2
luisguillermo dot quevedovelez at gmail dot com
2 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.
up
2
ashley at dcs dot warwick dot ac dot uk
12 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);
?>
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1
andy at arakka dot co dot th
9 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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1
Dennis Robinson from basnetworks dot net
5 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.
up
0
thalis at NOSPAMcs dot pitt dot edu
12 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()
   
}
}
?>
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