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

using  System; using  System.Collections.Generic; using  System.Linq; using  System.Text; using  System.IO; using  System.Diagnostics;   namespace  CA100 {      class  Program      {          //循環次數：5百萬次          const  int  COUNT = 5000000;          //外圍循環次數：5次          const  int  NUM = 5;          //準確測量運行時間          static  Stopwatch sWatch =  new  Stopwatch();          //每項時間          static  long  t1, t2;          //記錄日誌          static  StringBuilder sb =  new  StringBuilder();            static  void  Main()          {              string  src =  "C#測試IndexOf()LastIndexOf()Contains()StartsWith()EndsWith()5個方法的效率." ;              Console.WriteLine( "測試的字符串是："  + src +  "，測試次數"  + COUNT);              sb.AppendLine( "測試的字符串是："  + src +  "，測試次數"  + COUNT);              string  str =  "C" ;              //每項循環測試5次                int  i = 0;              Console.WriteLine( "\n'C'出如今首位時：\n" );              sb.AppendLine( "\r\n'C'出如今首位時：\r\n" );              for  (; i < NUM; i++)              {                  Console.WriteLine( "當前循環第{0}次\n" , i + 1);                  sb.AppendLine( "當前循環第"  + (i + 1) +  "次" );                  t1 += IndexOf(src, str);                  t2 += StartsWith(src, str);                  Console.WriteLine();                  sb.AppendLine();              }              Console.WriteLine( "IndexOf總時間："  + t1 +  "，平均時間："  + t1 / NUM);              sb.AppendLine( "IndexOf總時間："  + t1 +  "，平均時間："  + t1 / NUM);              Console.WriteLine( "StartsWith總時間："  + t2 +  "，平均時間："  + t2 / NUM);              sb.AppendLine( "StartsWith總時間："  + t2 +  "，平均時間："  + t2 / NUM);              Console.WriteLine();              sb.AppendLine();              t1 = 0;              t2 = 0;                str =  "StartsWith" ;              Console.WriteLine( "'StartsWith'出如今中間：\n" );              sb.AppendLine( "'StartsWith'出如今中間：\r\n" );              for  (i = 0; i < NUM; i++)              {                  Console.WriteLine( "當前循環第{0}次\n" , i + 1);                  sb.AppendLine( "當前循環第"  + (i + 1) +  "次" );                  t1 += IndexOf(src, str);                  t2 += Contains(src, str);                  Console.WriteLine();                  sb.AppendLine();              }                Console.WriteLine( "IndexOf總時間："  + t1 +  "，平均時間："  + t1 / NUM);              sb.AppendLine( "IndexOf總時間："  + t1 +  "，平均時間："  + t1 / NUM);              Console.WriteLine( "Contains總時間："  + t2 +  "，平均時間："  + t2 / NUM);              sb.AppendLine( "Contains總時間："  + t2 +  "，平均時間："  + 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( "當前循環第{0}次\n" , i + 1);                  sb.AppendLine( "當前循環第"  + (i + 1) +  "次" );                  t1 += LastIndexOf(src, str);                  t2 += EndsWith(src, str);                  Console.WriteLine();                  sb.AppendLine();              }                Console.WriteLine( "LastIndexOf總時間："  + t1 +  "，平均時間："  + t1 / NUM);              sb.AppendLine( "LastIndexOf總時間："  + t1 +  "，平均時間："  + t1 / NUM);              Console.WriteLine( "EndsWith總時間："  + t2 +  "，平均時間："  + t2 / NUM);              sb.AppendLine( "EndsWith總時間："  + t2 +  "，平均時間："  + t2 / NUM);              Console.WriteLine();              sb.AppendLine();                Console.WriteLine( "測試結束！" );              sb.AppendLine( "測試結束！" );                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花費: "  + sWatch.ElapsedMilliseconds +  "ms" );              sb.AppendLine( "IndexOf花費: "  + 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花費: "  + sWatch.ElapsedMilliseconds +  "ms" );              sb.AppendLine( "LastIndexOf花費: "  + 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花費: "  + sWatch.ElapsedMilliseconds +  "ms" );              sb.AppendLine( "StartsWith花費: "  + 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花費: "  + sWatch.ElapsedMilliseconds +  "ms" );              sb.AppendLine( "EndsWith花費: "  + 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花費: "  + sWatch.ElapsedMilliseconds +  "ms" );              sb.AppendLine( "Contains花費: "  + sWatch.ElapsedMilliseconds +  "ms" );              return  sWatch.ElapsedMilliseconds;          }      } }

 

針對三種狀況

1.判斷以字符串開頭

IndexOf和StartsWith

2.判斷是否包含字符串

IndexOf和Contains

3.判斷以字符串結尾

LastIndexOf和EndsWith

 

測試以某字符串爲開頭，以使用IndexOf爲最佳，有時，StartsWith也會比IndexOf快，概率較低。

測試包含字符串，以Contains最佳。

測試以某字符串結尾，雖然LastIndexOf速度略快，可是很差斷定，仍是採用EndsWith爲最佳。

 

 

 

 

 

 

 

 

 

[C#]  純文本查看 複製代碼

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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();         }     }

看測試後的效果

IndexOf執行五次

[C#]  純文本查看 複製代碼

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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執行五次

[C#]  純文本查看 複製代碼

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01 02 03 04 05 06

3毫秒 2 毫秒 2毫秒 3毫秒 2毫秒 2毫秒

差距這麼大我就很少說了，你們一看就明白Contains的性能要遠遠的超出IndexOf測試源碼下載