1     <script type="text/javascript">
 2         function factorial(num) {
 3             if (num <= 1) {
 4                 return 1;
 5             } else {
 6                 return num * arguments.callee(num - 1);
 7             }
 8         }
 9         var  trueFactorial = factorial;
10         factorial = function () {
11             return 0;
12         }
13         alert(trueFactorial(5));    //120
14         alert(factorial(5));        //0
15     </script>

 1  protected void Page_Load(object sender, EventArgs e)
 2     {
 3         TestFactorial();
 4     }
 5     public delegate int factorialDelegate(int num);     //定义递归函数委托
 6 
 7     private void TestFactorial()
 8     {
 9         factorialDelegate fdelegate = factorial;        //请注意与javascript函数对比
10         factorialDelegate trueFactorial = fdelegate;
11         fdelegate = returnZero;
12         int num1 = trueFactorial(5);                    //120
13         int num2 = fdelegate(5);                        //0
14     }
15 
16     private int returnZero(int num)
17     {
18         return 0;
19     }
20 
21     private int factorial(int num)
22     {
23         if (num <= 1)
24         {
25             return 1;
26         }
27         else
28         {
29             return num * factorial(num - 1);
30         }
31     }