Question

当文件存在时，我需要向用户显示一些消息，显示消息“文件存在...你要覆盖它吗？”

if (File.Exists(binaryFilePath))
{
    Program.DisplayMessage("The file: " + binaryFileName + " exist. You want to overwrite it? Y/N");
    string overwrite = Console.ReadLine();
    while (overwrite != null)
    {
        if (overwrite.ToUpper() == "Y")
        {
        WriteBinaryFile(frameCodes, binaryFilePath);

        } if (overwrite.ToUpper() == "N")
        {
        throw new IOException();
        overwrite = null;
        } if (overwrite.ToUpper() != "Y" && overwrite.ToUpper() != "N")
        {
        Program.DisplayMessage("!!Please Select a Valid Option!!");
        overwrite = Console.ReadLine();
        }
    }
}

如果用户写“Y”过程开始并完成正常...问题是如何停止？我试着用这个，但没有工作......

我该怎么做？

Answer 1

if (File.Exists(binaryFilePath))
{
  while (true)
  {
  Program.DisplayMessage("The file: " + binaryFileName + " already exist. Do you want to overwrite it? Y/N");
    string overwrite = Console.ReadLine();
    if (overwrite.ToUpper().Equals("Y"))
    {
      WriteBinaryFile(frameCodes, binaryFilePath);
      break;
    } 
    else if (overwrite.ToUpper().Equals("N"))
    {
      Console.WriteLine("Aborted by user.");
      break;
    } 
    else
    {
      Program.DisplayMessage("!!Please Select a Valid Option!!");
      overwrite = Console.ReadLine();
      continue; // not needed - for educational use only ;)
    }
  }
}

试试并学习基础知识（条件，循环，英语......）。然后你可以回来询问为什么在你的情况下抛出异常（特别是那个）;）

Answer 2

尝试使用break;打破循环（也使用if-else-if而不是if-if ..）

if (File.Exists(binaryFilePath))
{


    while (true)
    {
        Program.DisplayMessage("The file: " + binaryFileName + " exist. You  want to overwrite it? Y/N");
        string overwrite = Console.ReadLine();
        if (overwrite.ToUpper() == "Y")
        {
            WriteBinaryFile(frameCodes, binaryFilePath);
            break;

        } 
        else if (overwrite.ToUpper() == "N")
        {
            throw new IOException();
            overwrite = null;
            break;
        } 
        else if (overwrite.ToUpper() != "Y" && overwrite.ToUpper() != "N")
        {
            Program.DisplayMessage("!!Please Select a Valid Option!!");
            overwrite = Console.ReadLine();
        }
    }
}

虽然“N”之后的break;没用，但我希望你能处理你扔到别处的异常。

Answer 3

我相信，用户选择阅读应该委托给另一种方法。像这样：

static void Main(string[] args)
        {
            //...

            if (File.Exists(binaryFilePath))
            {
                if(ReadBool("The file: " + binaryFileName + " exist. You want to overwrite it? Y/N"))
                    WriteBinaryFile(frameCodes, binaryFilePath);
                else
                    throw new IOException();
            }
        }

static bool ReadBool(String question)
        {
            while (true)
            {
                Console.WriteLine(question);
                String r = (Console.ReadLine() ?? "").ToLower();
                if (r == "y")
                    return true;
                if (r == "n")
                    return false;
                Console.WriteLine("!!Please Select a Valid Option!!");
            }
        }

用户选项是/否

3 个答案: