IndexOf() LastIndexOf() Contains() StartsWith() EndsWith()方法比较

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Diagnostics;
 
namespace CA100
{
    class Program
    {
        //循环次数：5百万次
        const int COUNT = 5000000;
        //外围循环次数：5次
        const int NUM = 5;
        //准确测量运行时间
        static Stopwatch sWatch = new Stopwatch();
        //每项时间
        static long t1, t2;
        //记录日志
        static StringBuilder sb = new StringBuilder();
 
        static void Main()
        {
            string src = "C#测试IndexOf()LastIndexOf()Contains()StartsWith()EndsWith()5个方法的效率.";
            Console.WriteLine("测试的字符串是：" + src + "，测试次数" + COUNT);
            sb.AppendLine("测试的字符串是：" + src + "，测试次数" + COUNT);
            string str = "C";
            //每项循环测试5次
              int i = 0;
            Console.WriteLine("
'C'出现在首位时：
");
            sb.AppendLine("
'C'出现在首位时：
");
            for (; i < NUM; i++)
            {
                Console.WriteLine("当前循环第{0}次
", i + 1);
                sb.AppendLine("当前循环第" + (i + 1) + "次");
                t1 += IndexOf(src, str);
                t2 += StartsWith(src, str);
                Console.WriteLine();
                sb.AppendLine();
            }
            Console.WriteLine("IndexOf总时间：" + t1 + "，平均时间：" + t1 / NUM);
            sb.AppendLine("IndexOf总时间：" + t1 + "，平均时间：" + t1 / NUM);
            Console.WriteLine("StartsWith总时间：" + t2 + "，平均时间：" + t2 / NUM);
            sb.AppendLine("StartsWith总时间：" + t2 + "，平均时间：" + t2 / NUM);
            Console.WriteLine();
            sb.AppendLine();
            t1 = 0;
            t2 = 0;
 
            str = "StartsWith";
            Console.WriteLine("'StartsWith'出现在中间：
");
            sb.AppendLine("'StartsWith'出现在中间：
");
            for (i = 0; i < NUM; i++)
            {
                Console.WriteLine("当前循环第{0}次
", i + 1);
                sb.AppendLine("当前循环第" + (i + 1) + "次");
                t1 += IndexOf(src, str);
                t2 += Contains(src, str);
                Console.WriteLine();
                sb.AppendLine();
            }
 
            Console.WriteLine("IndexOf总时间：" + t1 + "，平均时间：" + t1 / NUM);
            sb.AppendLine("IndexOf总时间：" + t1 + "，平均时间：" + t1 / NUM);
            Console.WriteLine("Contains总时间：" + t2 + "，平均时间：" + t2 / NUM);
            sb.AppendLine("Contains总时间：" + t2 + "，平均时间：" + t2 / NUM);
            Console.WriteLine();
            sb.AppendLine();
            t1 = 0;
            t2 = 0;
 
            str = ".";
            Console.WriteLine("'.'出现在末尾：
");
            sb.AppendLine("'.'出现在末尾：
");
            for (i = 0; i < NUM; i++)
            {
                Console.WriteLine("当前循环第{0}次
", i + 1);
                sb.AppendLine("当前循环第" + (i + 1) + "次");
                t1 += LastIndexOf(src, str);
                t2 += EndsWith(src, str);
                Console.WriteLine();
                sb.AppendLine();
            }
 
            Console.WriteLine("LastIndexOf总时间：" + t1 + "，平均时间：" + t1 / NUM);
            sb.AppendLine("LastIndexOf总时间：" + t1 + "，平均时间：" + t1 / NUM);
            Console.WriteLine("EndsWith总时间：" + t2 + "，平均时间：" + t2 / NUM);
            sb.AppendLine("EndsWith总时间：" + t2 + "，平均时间：" + t2 / NUM);
            Console.WriteLine();
            sb.AppendLine();
 
            Console.WriteLine("测试结束！");
            sb.AppendLine("测试结束！");
 
            File.AppendAllText(@"d:
esults.txt", sb.ToString());
            Console.ReadLine();
        }
 
        static long IndexOf(string src, string str)
        {
            sWatch.Reset();
            sWatch.Start();
            for (int i = 0; i < COUNT; i++)
            {
                src.IndexOf(str);
            }
            sWatch.Stop();
 
            Console.WriteLine("IndexOf花费: " + sWatch.ElapsedMilliseconds + "ms");
            sb.AppendLine("IndexOf花费: " + sWatch.ElapsedMilliseconds + "ms");
            return sWatch.ElapsedMilliseconds;
        }
 
        static long LastIndexOf(string src, string str)
        {
            sWatch.Reset();
            sWatch.Start();
            for (int i = 0; i < COUNT; i++)
            {
                src.LastIndexOf(str);
            }
            sWatch.Stop();
 
            Console.WriteLine("LastIndexOf花费: " + sWatch.ElapsedMilliseconds + "ms");
            sb.AppendLine("LastIndexOf花费: " + sWatch.ElapsedMilliseconds + "ms");
            return sWatch.ElapsedMilliseconds;
        }
 
        static long StartsWith(string src, string str)
        {
            sWatch.Reset();
            sWatch.Start();
            for (int i = 0; i < COUNT; i++)
            {
                src.StartsWith(str);
            }
            sWatch.Stop();
 
            Console.WriteLine("StartsWith花费: " + sWatch.ElapsedMilliseconds + "ms");
            sb.AppendLine("StartsWith花费: " + sWatch.ElapsedMilliseconds + "ms");
            return sWatch.ElapsedMilliseconds;
        }
 
        static long EndsWith(string src, string str)
        {
            sWatch.Reset();
            sWatch.Start();
            for (int i = 0; i < COUNT; i++)
            {
                src.EndsWith(str);
            }
            sWatch.Stop();
 
            Console.WriteLine("EndsWith花费: " + sWatch.ElapsedMilliseconds + "ms");
            sb.AppendLine("EndsWith花费: " + sWatch.ElapsedMilliseconds + "ms");
            return sWatch.ElapsedMilliseconds;
        }
 
        static long Contains(string src, string str)
        {
            sWatch.Reset();
            sWatch.Start();
            for (int i = 0; i < COUNT; i++)
            {
                src.Contains(str);
            }
            sWatch.Stop();
 
            Console.WriteLine("Contains花费: " + sWatch.ElapsedMilliseconds + "ms");
            sb.AppendLine("Contains花费: " + sWatch.ElapsedMilliseconds + "ms");
            return sWatch.ElapsedMilliseconds;
        }
    }
}

针对三种情况

1.判断以字符串开头

IndexOf和StartsWith

2.判断是否包含字符串

IndexOf和Contains

3.判断以字符串结尾

LastIndexOf和EndsWith

测试以某字符串为开头，以使用IndexOf为最佳，有时，StartsWith也会比IndexOf快，几率较低。

测试包含字符串，以Contains最佳。

测试以某字符串结尾，虽然LastIndexOf速度略快，但是不好判定，还是采用EndsWith为最佳。

[C#] 纯文本查看复制代码

public partial class Form1 : Form
   {
       public Form1()
       {
           InitializeComponent();
       }
       string url = "http://www.0398jobs.com/index.htm";
       private void Form1_Load(object sender, EventArgs e)
       {
 
       }
       //
       private void button1_Click(object sender, EventArgs e)
       {
           label1.Text = string.Empty;
           DateTime st = DateTime.Now;
           for (int i = 0; i < 10000; i++)
           {
               if (url.IndexOf("job.com") > 0 || url.IndexOf("jobs.com") > 0)
               {
 
               }
           }
           label1.Text = (DateTime.Now - st).Milliseconds.ToString();
       }
       //Contains
       private void button2_Click(object sender, EventArgs e)
       {
           label1.Text = string.Empty;
           DateTime st = DateTime.Now;
           for (int i = 0; i < 10000; i++)
           {
               if (url.Contains("job.com") || url.Contains("jobs.com"))
               {
 
               }
           }
           label1.Text = (DateTime.Now-st).Milliseconds.ToString();
       }
   }

看测试后的效果

IndexOf执行五次

[C#] 纯文本查看复制代码

38毫秒
36 毫秒
37毫秒
36毫秒
36毫秒
39毫秒

Contains执行五次

[C#] 纯文本查看复制代码

3毫秒
2 毫秒
2毫秒
3毫秒
2毫秒
2毫秒

差距这么大我就不多说了，大家一看就明白
Contains的性能要远远的超出IndexOf
测试源码下载