C#使用for循环来计算阶乘

using System;
using System.Collections.Generic;
using System.linq;
using System.Text;

namespace factorial {
   class Test {
      static voID Main(string[] args) {
         int i, res;
         int value = 5;
         res = value;
         for (i = value - 1; i >= 1; i--) {
            res = res * i;
         }
         Console.Writeline("\nFactorial of "+value+" = "+res);
         Console.Readline();
      }
   }
}