C#错误和异常处理典型例子

检查用户输入的是否是一个0-5中间的数字： 多重catch块

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



namespace ExceptionDemo

{

    class Program

    {

        static void Main(string[] args)

        {

            string userInput;



            while (true)

            {

                try

                {

                    Console.Write("Input a number between 0 and 5" + "(or just hit return to exist)>");

                    userInput = Console.ReadLine();



                    if (userInput == "")

                        break;



                    int index = Convert.ToInt32(userInput);



                    if (index < 0 || index > 5)

                        throw new IndexOutOfRangeException("You typed in  " + userInput);



                    Console.WriteLine("Your number was " + index);

                }

                catch (IndexOutOfRangeException ex)

                {

                    Console.WriteLine("Exception: " + "Number should between 0 and 5." + ex.Message);

                }

                catch (Exception ex)

                {

                    Console.WriteLine("An exception was thrown. Message was: {0}" + ex.Message);

                }

                catch

                {

                    Console.WriteLine("Some other exception has occured");

                }

                finally

                {

                    Console.WriteLine("Thank you");

                }

            }

        }

    }

}

当输入的是非0-5之间的数字的时候，抛出的第一个异常，如果是一个字符串，抛出的第二个异常。第三个异常不带参数，这个catch块处理的是其他没有用C#编程的代码。

 

下面这个是MSDN一个try…finally的异常处理

static void CodeWithCleanup()

        {

            System.IO.FileStream file = null;

            System.IO.FileInfo fileInfo = null;



            try

            {

                fileInfo = new System.IO.FileInfo("C:\\file.txt");



                file = fileInfo.OpenWrite();

                file.WriteByte(0xF);

            }

            catch (System.Exception e)

            {

                System.Console.WriteLine(e.Message);

            }

            finally

            {

                if (file != null)

                {

                    file.Close();

                }

            }

        }