# func_num_args

(PHP 4, PHP 5, PHP 7)

func_num_args — 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 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

- 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