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

时间  2019-11-09
标签 indexof lastindexof contains startswith endswith 方法 比较 繁體版
原文   原文链接
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( "\n'C'出如今首位时：\n" );
             sb.AppendLine( "\r\n'C'出如今首位时：\r\n" );
             for  (; i < NUM; i++)
             {
                 Console.WriteLine( "当前循环第{0}次\n" , 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'出如今中间：\n" );
             sb.AppendLine( "'StartsWith'出如今中间：\r\n" );
             for  (i = 0; i < NUM; i++)
             {
                 Console.WriteLine( "当前循环第{0}次\n" , 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( "'.'出如今末尾：\n" );
             sb.AppendLine( "'.'出如今末尾：\r\n" );
             for  (i = 0; i < NUM; i++)
             {
                 Console.WriteLine( "当前循环第{0}次\n" , 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:\results.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;
         }
     }
}

 

针对三种状况性能

1.判断以字符串开头测试

IndexOf和StartsWithui

2.判断是否包含字符串url

IndexOf和Containsspa

3.判断以字符串结尾pwa

LastIndexOf和EndsWith日志

 

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，概率较低。code

测试包含字符串，以Contains最佳。orm

测试以某字符串结尾，虽然LastIndexOf速度略快，可是很差断定，仍是采用EndsWith为最佳。htm

 

 

 

 

 

 

 

 

 

[C#]  纯文本查看 复制代码
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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
?
01
02
03
04
05
06
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
?
01
02
03
04
05
06
3毫秒
2 毫秒
2毫秒
3毫秒
2毫秒
2毫秒

差距这么大我就很少说了，你们一看就明白Contains的性能要远远的超出IndexOf测试源码下载

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