循环优化技巧一 —— 大循环在内，小循环主外

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

namespace ConsoleTest
{
    class Program
    {
        const string CONSOLE_EXIT = "exit";

        static void Main(string[] args)
        {
            PerformanceMonitor pm = new PerformanceMonitor();
            pm.OnCallMethod += new PerformanceMonitor.CallMethod(test);

            Console.WriteLine("请按照格式 [整数1,整数2] 输入数据 (输入 {0} 结束) ...", CONSOLE_EXIT);

            // 循环提示输入数据
            int outter = 0;
            int inner = 0;
            string str = string.Empty;
            while(true)
            {
                str = Console.ReadLine();
                if (str.Trim().ToLower().Equals(CONSOLE_EXIT))
                {
                    break;
                }

                if (str.IndexOf(',') < 1)
                {
                    continue;
                }
                outter = int.Parse(str.Split(new char[] {','  })[0]);
                inner =  int.Parse(str.Split(new char[] { ',' })[1]);

                pm.Test(outter, inner);
            }

            Console.WriteLine("Press any key to continue ...");
            Console.ReadLine();
        }

        /// <summary>
        /// 测试函数
        /// </summary>
        /// <param name="outter">外层循环</param>
        /// <param name="inner">内层循环</param>
        private static void test(int outter, int inner)
        {
            StringBuilder builder = new StringBuilder();
            // 测试主体部分
            for (int i = 0; i < outter; i++)
            {
                // 外层循环代码块
                builder.AppendFormat("Outer counter: {0}/t/n",i.ToString());
                for (int j = 0; j < inner; j++)
                {
                    // 内层循环代码块
                    builder.AppendFormat("Inner counter: {0}/t", j.ToString());
                }
                builder.Append("/n");
            }

            Console.WriteLine(builder.ToString());
        }
    }

    public class PerformanceMonitor
    {
        // 定制事件
        public delegate void CallMethod(int outter, int inner);
        public event CallMethod OnCallMethod;
        // 记录时间
        private double mCostTime = 0;

        /// <summary>
        /// 调用函数进行测试
        /// </summary>
        /// <param name="outter">外层数据</param>
        /// <param name="inner">内层数据</param>
        public void WriteText(int outter, int inner)
        {
            DateTime start = DateTime.Now;
            if (null != this.OnCallMethod)
            {
                this.OnCallMethod(outter, inner);
            }
            DateTime end = DateTime.Now;
            this.mCostTime = end.Subtract(start).TotalMilliseconds;
        }

        /// <summary>
        /// 显示测试信息
        /// </summary>
        /// <param name="o">数据一</param>
        /// <param name="i">数据二</param>
        public void Test(int o, int i)
        {
            StringBuilder builder = new StringBuilder("/t外层/t内层/t耗时(ms)/n");
            int max = 0;
            int min = 0;
            double time1 = 0;
            double time2 = 0;

            // 确定数据大小值
            max = (o >= i) ? o : i;
            min = (max == o) ? i : o;

            // 大数在 外层 循环
            this.WriteText(max, min);
            time1 = this.mCostTime;
            builder.AppendFormat("/t{0}/t{1}/t{2}/n", max.ToString(), min.ToString(), time1.ToString("#.##"));

            // 大数在 内层 循环
            this.WriteText(min, max);
            time2 = this.mCostTime;
            builder.AppendFormat("/t{0}/t{1}/t{2}/n", min.ToString(), max.ToString(), time2.ToString("#.##"));

            // 记录时间和效率
            double ms = time1 - time2;
            double gs = (1 - time2/time1) * 100;
            builder.AppendFormat("优化：/t节时 {0} ms/t效率 {1}%", (ms.ToString("#.##").Length < 1) ? "0.00" : ms.ToString("#.##"), (gs.ToString("#.##").Length < 1) ? "0.00" : gs.ToString("#.##"));

            // 用颜色区分一下
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine(builder.ToString());
            Console.ResetColor();
        }

    }
}