php动态获取函数参数

<?php
function  demo ()
{
    $numargs  =  func_num_args ();
    echo  "参数个数为:  $numargs \n" ;
}
demo ( ‘a‘ ,  ‘b‘ ,  ‘c‘ );

<?php
function  demo ()
{
    $args = func_get_args();
    echo "传入的参数分别为:";
    var_dump($args);
}
demo ( ‘a‘ ,  ‘b‘ ,  ‘c‘ );

传入的参数分别为:
array (size=3)
  0 => string ‘a‘ (length=1)
  1 => string ‘b‘ (length=1)
  2 => string ‘c‘ (length=1)

<?php
function  demo ()
{
    $numargs  =  func_num_args ();
    echo  "参数个数为:  $numargs <br />" ;
    $args = func_get_args();
    if ( $numargs  >=  2 ) {
        echo  "第二个参数为: "  .  func_get_arg ( 1 ) .  "<br />" ;
    }
}
demo ( ‘a‘ ,  ‘b‘ ,  ‘c‘ );

参数个数为: 3
第二个参数为: b