c#中的异常处理

 class Program
    {
        static string[] eTypes = { "none", "simple", "index", "nested index" };

        static void Main(string[] args)
        {
            foreach (string etype in eTypes)
            {
                try
                {
                    Console.WriteLine("Main() try block reached.");
                    Console.WriteLine("ThrowException(\"{0}\") called.", etype);
                    ThrowException(etype);
                    Console.WriteLine("Main() try block continues.");
                }
                catch (System.IndexOutOfRangeException e)
                {
                    Console.WriteLine("Main() System.IndexOutOfRangeException catch"
                        + "block reached.Message:\n\"{0}\"", e.Message);

                }
                catch
                {
                    Console.WriteLine("Main() general catch block reached.");
                }
                finally
                {
                    Console.WriteLine("Main() finally block reached.");

                
                }
            }


            Console.ReadKey();

        }

        static void ThrowException(string etype)
        {
           // throw new NotImplementedException();
            Console.WriteLine("ThrowException{\"{0}\"} reached.",etype);
            switch(etype)
            {
                case "none":
                    Console.WriteLine("Not throwing an exception.");
                    break;
                case "simple":
                    Console.WriteLine("Throwing System.Exception");
                    throw (new System.Exception());

                    break;
                case "index":
                    Console.WriteLine("Throwing System.IndexOutOfRangeException.");
                    eTypes[4] = "error";
                    break;
                case "nested index":
                    try
                    {
                        Console.WriteLine("ThrowException(\"nested index\") " + "try block reached.");
                        Console.WriteLine("ThrowException(\"index\") called.");
                        ThrowException("index");


                    }
                    catch
                    {
                        Console.WriteLine("ThrowException(\"nested index\") general" + "catch block reached.");

                    }
                    finally
                    {
                        Console.WriteLine("ThrowException(\"nested index\") finally"+"block reached");

                    }
                    break;
                    
            
            }
        }
    }