计算1-100之间的所有整数的和

求1-100所有整数和：

 1   class PRogram 2     { 3         static void Main(string[] args) 4         { 5            int sum= GetSum(1,100); 6             Console.WriteLine("1-100之间所有整数和{0}",sum); 7             Console.ReadKey(); 8         } 9         /// <summary>10         /// 1-100之间的所有整数和11         /// </summary>12         /// <param name="p1"></param>13         /// <param name="p2"></param>14         /// <returns></returns>15         private static int GetSum(int p1, int p2)16         {17             int sum = 0;18             for (int i = p1; i <= p2; i++)19             {20                 sum += i;21             }22             return sum;23 24         }25     }