func_num_args()

(PHP 4, PHP 5, PHP 7)

Returns the number of arguments passed to the function

说明

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

以上例程会输出：

Number of arguments: 3

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

test.php

fna.php 

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

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: 

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:

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:

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 

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();
   $args_list = func_get_args();
   echo '
';
   var_dump($args_list);
   echo '
';
 }
}
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: 
func_num_args() can be used in conjunction with named arguments, also. For example: 
 

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