StringBuilder初始长度很重要

和别人打赌的，今晚测试。只有代码和截图

 

代码

   
     

    
      
    
      class
    
       Program
 {
 
    
      static
    
       
    
      void
    
       Main(
    
      string
    
      [] args)
 {
 Stopwatch watch 
    
      =
    
       
    
      new
    
       Stopwatch();
 
 watch.Reset();
 watch.Start();

 StrBuilderWithInitialLength();
 watch.Stop();
 Console.WriteLine(watch.ElapsedMilliseconds);
 watch.Reset();
 watch.Start();
 StrBuilderWithoutInitialLength();
 watch.Stop();
 Console.WriteLine(watch.ElapsedMilliseconds);

 }

 
 
    
      static
    
       
    
      void
    
       StrBuilderWithInitialLength()
 {
 StringBuilder sb 
    
      =
    
       
    
      new
    
       StringBuilder(
    
      80000000
    
      );
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       
    
      40000000
    
      ; i
    
      ++
    
      )
 {
 sb.Append(
    
      "
    
      12
    
      "
    
      );
 }
 }

 
    
      static
    
       
    
      void
    
       StrBuilderWithoutInitialLength()
 {
 StringBuilder sb 
    
      =
    
       
    
      new
    
       StringBuilder();
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       
    
      40000000
    
      ; i
    
      ++
    
      )
 {
 sb.Append(
    
      "
    
      12
    
      "
    
      );
 }
 }
 }
   
     

运行时间截图：