如何获得函数本身有多少个参数

<!--?php <br /--><br>function hello($param1,$param2,...){<br>
echo 'function name is:'. __FUNCTION__; // get function itself name<br>
// how to get how many parameters in these function ,<br>
echo '<br>has ? parameters';<br>}<br>hello();

<br>function hello(){<br>    echo 'function name is:'. __FUNCTION__; // get function itself name<br>    // how to get how many parameters in these function ,<br>    echo '<br>has '.func_num_args().' parameters<br>';<br>    $params = func_get_args();<br>    foreach($params as $param){<br>        echo $param.'<br>';<br>    }<br>}<br>hello(1,2,3);<br>