stringbuilder和string拼字符串的性能，有点吓人。

           System.Text.StringBuilder sb = new System.Text.StringBuilder();
            int i = 0;
            long StartTime = DateTime.Now.Ticks;
            while (i < 80000)
            {
                sb.Append(i.ToString());
                i++;
            }
            long EndTime = DateTime.Now.Ticks;

            Console.WriteLine("时间:" + (EndTime - StartTime) + "\t Capacity:" + sb.Capacity + "\t Length:"

            + sb.Length);


            string sb1 = null;
            i = 0;
            StartTime = DateTime.Now.Ticks;
            while (i < 80000)
            {
                sb1 += i;
                i++;
            }
            EndTime = DateTime.Now.Ticks;
            Console.WriteLine("时间:" + (EndTime - StartTime));
            Console.Read();