用"类"来代替"递归方法"，用php举例。

<?php

//一个楼梯有n个台阶，每次上一个或两个台阶，共有多少种上法, 每种走法的步骤是什么样的.
define('totle_step', 10);
$p = '';
$obj = new step($p, 0, 0);
$obj->go();

class step{

 var $parent;
 var $count;
 var $step;
 var $son1;
 var $son2;

 function step(&$parent, $step, $count){
        $this->parent = &$parent;
        $this->step = $step;
        $this->count = $count + $step;
 }

 function go(){
  if($this->count==totle_step)
   $this->callback();
        if($this->count<=totle_step-1){
         $this->son1 = new step($this, 1, $this->count);
         $this->son1->go();
        }
        if($this->count<=totle_step-2){
         $this->son2 = new step($this, 2, $this->count);
         $this->son2->go();
        }
 }

 function callback($str=''){
        if($this->parent!=null){
         $str = $this->step.$str;
         $this->parent->callback('--'.$str);
        }else{
         echo $str.'<br>';
        }
 }
}
?>