Main 方法包含带有 StreamReader 语句的 Try 块,该语句打开名为 data.txt

using System;


  
  using System.IO;


  
  using System.Security.Permissions;


  
  //
  
   Security permission request.
  
  

[assembly:FileIOPermissionAttribute(SecurityAction.RequestMinimum, All = 
  
  @"
  
  c:\data.txt
  
  ")]


  
  public 
  
  class ProcessFile {

    
  
  public 
  
  static 
  
  void Main() {

        
  
  try {

            StreamReader sr = File.OpenText(
  
  "
  
  data.txt
  
  ");

            Console.WriteLine(
  
  "
  
  The first line of this file is {0}
  
  ", sr.ReadLine());    

        }

        
  
  catch(Exception e) {

            Console.WriteLine(
  
  "
  
  An error occurred: '{0}'
  
  ", e);

        }

    }

}

此示例阐释捕捉任何异常的基本 Catch 语句。一般而言,好的编程做法是捕捉特定类型的异常而不是使用基本 Catch 语句。有关捕捉特定异常的更多信息,请参见 在 Catch 块中使用特定异常