func_num_args()

(PHP 4, PHP 5, PHP 7)

Returns the number of arguments passed to the function

说明

func_num_args(void): int

Gets the number of arguments passed to the function.

This function may be used in conjunction withfunc_get_arg()andfunc_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

错误／异常

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

范例

Example #1func_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 #2func_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

• func_get_arg() 返回参数列表的某一项
• func_get_args() 返回一个包含函数参数列表的数组
• ReflectionFunctionAbstract::getNumberOfParameters() 获取参数数目

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!");
?>

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.

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()
  }
}
?>

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.

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

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);
?>

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>";
}
?>