当在c#中构建Windows控制台应用程序时,是否有可能写入控制台而不必扩展当前行或去到新行?例如,如果我想显示一个百分比,表示一个流程离完成有多近,我只需要在游标所在的同一行上更新该值,而不必将每个百分比放在新行上。

这可以用“标准”c#控制台应用程序来实现吗?


当前回答

我在vb.net上寻找同样的解决方案,我发现了这个,它很棒。

然而,@JohnOdom建议了一个更好的方法来处理空格,如果前一个空格比当前空格大。

我在vb.net做了一个函数,认为有人可以得到帮助。

这是我的代码:

Private Sub sPrintStatus(strTextToPrint As String, Optional boolIsNewLine As Boolean = False)
    REM intLastLength is declared as public variable on global scope like below
    REM intLastLength As Integer
    If boolIsNewLine = True Then
        intLastLength = 0
    End If
    If intLastLength > strTextToPrint.Length Then
        Console.Write(Convert.ToChar(13) & strTextToPrint.PadRight(strTextToPrint.Length + (intLastLength - strTextToPrint.Length), Convert.ToChar(" ")))
    Else
        Console.Write(Convert.ToChar(13) & strTextToPrint)
    End If
    intLastLength = strTextToPrint.Length
End Sub

其他回答

SetCursorPosition方法适用于多线程场景,而其他两个方法则不能

以下是我对s soosh和0xA3的回答的看法。 它可以在更新旋转器的同时用用户消息更新控制台,并且还有一个运行时间指示器。

public class ConsoleSpiner : IDisposable
{
    private static readonly string INDICATOR = "/-\\|";
    private static readonly string MASK = "\r{0} {1:c} {2}";
    int counter;
    Timer timer;
    string message;

    public ConsoleSpiner() {
        counter = 0;
        timer = new Timer(200);
        timer.Elapsed += TimerTick;
    }

    public void Start() {
        timer.Start();
    }

    public void Stop() {
        timer.Stop();
        counter = 0;
    }

    public string Message {
        get { return message; }
        set { message = value; }
    }

    private void TimerTick(object sender, ElapsedEventArgs e) {
        Turn();
    }

    private void Turn() {
        counter++;
        var elapsed = TimeSpan.FromMilliseconds(counter * 200);
        Console.Write(MASK, INDICATOR[counter % 4], elapsed, this.Message);
    }

    public void Dispose() {
        Stop();
        timer.Elapsed -= TimerTick;
        this.timer.Dispose();
    }
}

用法是这样的:

class Program
{
    static void Main(string[] args)
    {
        using (var spinner = new ConsoleSpiner())
        {
            spinner.Start();
            spinner.Message = "About to do some heavy staff :-)"
            DoWork();
            spinner.Message = "Now processing other staff".
            OtherWork();
            spinner.Stop();
        }
        Console.WriteLine("COMPLETED!!!!!\nPress any key to exit.");

    }
}

我只需要使用divo的ConsoleSpinner类。我的远没有那么简洁,但我不喜欢这个类的用户必须编写自己的while(true)循环。我追求的是这样的经历:

static void Main(string[] args)
{
    Console.Write("Working....");
    ConsoleSpinner spin = new ConsoleSpinner();
    spin.Start();

    // Do some work...

    spin.Stop(); 
}

我用下面的代码实现了它。由于我不希望Start()方法阻塞,我不希望用户不得不担心编写while(spinFlag)类循环,并且我希望同时允许多个旋转器,因此我必须生成一个单独的线程来处理旋转。这意味着代码要复杂得多。

此外,我没有做那么多多线程,所以有可能(甚至可能)我在那里留下了一个或三个微妙的错误。但到目前为止,它似乎运行得很好:

public class ConsoleSpinner : IDisposable
{       
    public ConsoleSpinner()
    {
        CursorLeft = Console.CursorLeft;
        CursorTop = Console.CursorTop;  
    }

    public ConsoleSpinner(bool start)
        : this()
    {
        if (start) Start();
    }

    public void Start()
    {
        // prevent two conflicting Start() calls ot the same instance
        lock (instanceLocker) 
        {
            if (!running )
            {
                running = true;
                turner = new Thread(Turn);
                turner.Start();
            }
        }
    }

    public void StartHere()
    {
        SetPosition();
        Start();
    }

    public void Stop()
    {
        lock (instanceLocker)
        {
            if (!running) return;

            running = false;
            if (! turner.Join(250))
                turner.Abort();
        }
    }

    public void SetPosition()
    {
        SetPosition(Console.CursorLeft, Console.CursorTop);
    }

    public void SetPosition(int left, int top)
    {
        bool wasRunning;
        //prevent other start/stops during move
        lock (instanceLocker)
        {
            wasRunning = running;
            Stop();

            CursorLeft = left;
            CursorTop = top;

            if (wasRunning) Start();
        } 
    }

    public bool IsSpinning { get { return running;} }

    /* ---  PRIVATE --- */

    private int counter=-1;
    private Thread turner; 
    private bool running = false;
    private int rate = 100;
    private int CursorLeft;
    private int CursorTop;
    private Object instanceLocker = new Object();
    private static Object console = new Object();

    private void Turn()
    {
        while (running)
        {
            counter++;

            // prevent two instances from overlapping cursor position updates
            // weird things can still happen if the main ui thread moves the cursor during an update and context switch
            lock (console)
            {                  
                int OldLeft = Console.CursorLeft;
                int OldTop = Console.CursorTop;
                Console.SetCursorPosition(CursorLeft, CursorTop);

                switch (counter)
                {
                    case 0: Console.Write("/"); break;
                    case 1: Console.Write("-"); break;
                    case 2: Console.Write("\\"); break;
                    case 3: Console.Write("|"); counter = -1; break;
                }
                Console.SetCursorPosition(OldLeft, OldTop);
            }

            Thread.Sleep(rate);
        }
        lock (console)
        {   // clean up
            int OldLeft = Console.CursorLeft;
            int OldTop = Console.CursorTop;
            Console.SetCursorPosition(CursorLeft, CursorTop);
            Console.Write(' ');
            Console.SetCursorPosition(OldLeft, OldTop);
        }
    }

    public void Dispose()
    {
        Stop();
    }
}

到目前为止,我们有三个相互竞争的替代方案:

Console.Write("\r{0}   ", value);                      // Option 1: carriage return
Console.Write("\b\b\b\b\b{0}", value);                 // Option 2: backspace
{                                                      // Option 3 in two parts:
    Console.SetCursorPosition(0, Console.CursorTop);   // - Move cursor
    Console.Write(value);                              // - Rewrite
}

我一直使用控制台。CursorLeft = 0,第三个选项的变体,所以我决定做一些测试。下面是我使用的代码:

public static void CursorTest()
{
    int testsize = 1000000;

    Console.WriteLine("Testing cursor position");
    Stopwatch sw = new Stopwatch();
    sw.Start();
    for (int i = 0; i < testsize; i++)
    {
        Console.Write("\rCounting: {0}     ", i);
    }
    sw.Stop();
    Console.WriteLine("\nTime using \\r: {0}", sw.ElapsedMilliseconds);

    sw.Reset();
    sw.Start();
    int top = Console.CursorTop;
    for (int i = 0; i < testsize; i++)
    {
        Console.SetCursorPosition(0, top);        
        Console.Write("Counting: {0}     ", i);
    }
    sw.Stop();
    Console.WriteLine("\nTime using CursorLeft: {0}", sw.ElapsedMilliseconds);

    sw.Reset();
    sw.Start();
    Console.Write("Counting:          ");
    for (int i = 0; i < testsize; i++)
    {        
        Console.Write("\b\b\b\b\b\b\b\b{0,8}", i);
    }

    sw.Stop();
    Console.WriteLine("\nTime using \\b: {0}", sw.ElapsedMilliseconds);
}

在我的机器上,我得到了以下结果:

退格:25.0秒 回车:28.7秒 SetCursorPosition: 49.7秒

此外,SetCursorPosition引起了明显的闪烁,我没有观察到任何一个替代方案。所以,道德是尽可能使用退格或回车,谢谢你教我一个更快的方法来做到这一点,所以!


Update: In the comments, Joel suggests that SetCursorPosition is constant with respect to the distance moved while the other methods are linear. Further testing confirms that this is the case, however constant time and slow is still slow. In my tests, writing a long string of backspaces to the console is faster than SetCursorPosition until somewhere around 60 characters. So backspace is faster for replacing portions of the line shorter than 60 characters (or so), and it doesn't flicker, so I'm going to stand by my initial endorsement of \b over \r and SetCursorPosition.

    public void Update(string data)
    {
        Console.Write(string.Format("\r{0}", "".PadLeft(Console.CursorLeft, ' ')));
        Console.Write(string.Format("\r{0}", data));
    }