字符串中判断存在的几种模式和效率(string.contains、string.IndexOf、Regex.Match)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace ExistsInString
{
    class Program
    {
        static void Main(string[] args)
        {
            string str0 = "|456|";
            string str1 = "|444|";
            string str2 = "|111|222|333|444|555|666|777|888|999|000|";

            //------------------------------------------
            //String.Contains方法

            if (str2.Contains(str0))
                Console.WriteLine("String.Contains->true");
            else
                Console.WriteLine("String.Contains->false");

            if (str2.Contains(str1))
                Console.WriteLine("String.Contains->true");
            else
                Console.WriteLine("String.Contains->false");

            //------------------------------------------
            //String.IndexOf方法
            int val1 = str2.IndexOf(str0);//不存在返回-1
            Console.WriteLine("String.IndexOf(no exists)->" + val1);
            int val2 = str2.IndexOf(str1);//存在返回str1首字符所在str2中的位置(>=0)
            Console.WriteLine("String.IndexOf(exists)->" + val2);

            //------------------------------------------
            //正则匹配方法
            if (Regex.Match(str2, "[|]456[|]").Success)
                Console.WriteLine("Regex.Match(no exists)->true");
            else
                Console.WriteLine("Regex.Match(no exists)->false");

            if (Regex.Match(str2, "[|]444[|]").Success)
                Console.WriteLine("Regex.Match(exists)->true");
            else
                Console.WriteLine("Regex.Match(exists)->false");

            Console.ReadKey();

            /*
             *如果上述三种方式都处理大量数据，效率如何呢？
             *以下循环六组数据说明 
             */

            int loopCount = (int)10e6;
            DateTime lasttime = DateTime.Now;
            DateTime nowtime = DateTime.Now;

            for (int loop = 1; loop < 7; loop++)
            {
                Console.WriteLine("\r\nloop " + loop + " >>>>>>>");

                //------------------------------------------
                //String.Contains方法

                //no exists
                lasttime = DateTime.Now;
                for (int i = 0; i < loopCount; i++)
                    if (str2.Contains(str0)) { };
                nowtime = DateTime.Now;
                TimeSpan tsStrConNoExists = nowtime - lasttime;

                //exists
                lasttime = DateTime.Now;
                for (int i = 0; i < loopCount; i++)
                    if (str2.Contains(str1)) { };
                nowtime = DateTime.Now;
                TimeSpan tsStrConExists = nowtime - lasttime;


                //------------------------------------------
                //String.IndexOf方法

                //no exists
                lasttime = DateTime.Now;
                for (int i = 0; i < loopCount; i++)
                    if (str2.IndexOf(str0) >= 0) { };//上述已经提到不存在返回-1，存在返回一个非负整数，这里为什么不用 == -1 ，而是用了 >= 0 ，这是一个值得深思的问题？
                nowtime = DateTime.Now;
                TimeSpan tsStrIndNoExists = nowtime - lasttime;

                //exists
                lasttime = DateTime.Now;
                for (int i = 0; i < loopCount; i++)
                    if (str2.IndexOf(str1) >= 0) { };
                nowtime = DateTime.Now;
                TimeSpan tsStrIndExists = nowtime - lasttime;

                //------------------------------------------
                //Regex.Match方法

                //no exists
                Regex Reg0 = new Regex("[|]456[|]");
                lasttime = DateTime.Now;
                for (int i = 0; i < loopCount; i++)
                    if (Reg0.Match(str2).Success) { };
                nowtime = DateTime.Now;
                TimeSpan tsStrRegNoExists = nowtime - lasttime;

                //exists
                Regex Reg1 = new Regex("[|]444[|]");
                lasttime = DateTime.Now;
                for (int i = 0; i < loopCount; i++)
                    if (Reg1.Match(str2).Success) { };
                nowtime = DateTime.Now;
                TimeSpan tsStrRegExists = nowtime - lasttime;

                Console.WriteLine("no exists >>>");
                Console.WriteLine("tsStrConNoExists = " + tsStrConNoExists.Milliseconds);
                Console.WriteLine("tsStrIndNoExists = " + tsStrIndNoExists.Milliseconds);
                Console.WriteLine("tsStrRegNoExists = " + tsStrRegNoExists.Milliseconds);
                Console.WriteLine("exists >>>");
                Console.WriteLine("tsStrConExists = " + tsStrConExists.Milliseconds);
                Console.WriteLine("tsStrIndExists = " + tsStrIndExists.Milliseconds);
                Console.WriteLine("tsStrRegExists = " + tsStrRegExists.Milliseconds);
            }

            Console.ReadKey();
        }
    }
}