func_num_args

(PHP 4, PHP 5, PHP 7, PHP 8)

func_num_args — Returns the number of arguments passed to the function

说明

func_num_args ( ) : int

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.

返回值

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

更新日志

版本 说明
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.

错误／异常

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

范例

Example #1 func_num_args() example

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

foo(1, 2, 3);   
?>

以上例程会输出：

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

注释

Note:

因为函数依赖于当前作用域以确定参数的细节，所以在 5.3.0 以前的版本中不能用作函数的参数。如必须传递此值时，可将结果赋与一个变量，然后用此变量进行传递。

参见

User Contributed Notes

tongcheong77 at gmail dot com 20-Jun-2017 06:12
If you are using PHP 7 and func_num_args is in your base class which you extended, you can pass your arguments with the 'spat' operator.

class Sql {

public function doGetWhere(...$args) {

$num_args = func_num_args();
      $args_list = func_get_args();

      echo '<pre>';
      var_dump($args_list);
      echo '<pre>';
  }
}

class Member extends Sql {

public function getWhere(...$args) {

   $this->doGetWhere(...$args);

      }
}

$member = new Member();
$member->getWhere('first_name','last_name','userlevel','email','where','email','=',$sub_email);

However, take note that if you 'new up' the 'Sql' class in your 'Member' class above, instead of extending it, you will not need to pass your arguments as a variable. Just my two cents. -Bruce tong
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.
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()
    }
}
?>