如何在 C# 控制台应用程序的行首允许用户输入？

Question

我知道我可以使用 Console.ReadLine() 来允许用户输入，但它只允许用户从光标所在的位置输入，我想要一种能够允许用户从行首输入的方法（超过整行），而不仅仅是光标所在的位置。例如：

for (int i = 1;i <= 5;i++) Console.Write(i+" ");
string x = Console.ReadLine();

这将给出以下输出：

1 2 3 4 5 _

其中'_'指的是光标，这样，用户将只能从光标位置开始书写——他也不能使用退格键来删除前面的字符。那么如何在光标不在行首时允许用户输入整行呢？

Answer 1

这是准备好使用自定义输入处理的示例。 当然，这需要对性能进行一些调整，但它应该让您知道从哪里开始。

    static void Main(string[] args)
    {
        List<char> outputString = new List<char>();
        outputString = "test".ToCharArray().ToList();
        //If there is something in outputString write it to buffer and set cursor position
        if (outputString.Count > 0)
        {
            Console.Write(outputString.Select(x => x.ToString()).Aggregate((x, y) => x + y));
        }

        while (true)
        {
            //This will read user input but it will not print it to the console window 
            var key = Console.ReadKey(true);
            //Allow user maniputate cursor to the right
            //Here you can add another condition to prevent line overflow or some constrains
            //if(Console.CursorLeft < 30)
            if (key.Key == ConsoleKey.RightArrow && Console.CursorLeft < outputString.Count)
            {
                Console.SetCursorPosition(Console.CursorLeft + 1, Console.CursorTop);
            }
            else if (key.Key == ConsoleKey.LeftArrow && Console.CursorLeft > 0)
            {
                Console.SetCursorPosition(Console.CursorLeft - 1, Console.CursorTop);
            }
            //Here you should add all keys that your input should take, special characters are ok above ASCII number 32 which is space
            else if (key.KeyChar >= 48 && key.KeyChar <= 57 || //Read numbers
                key.KeyChar >= 64 && key.KeyChar <= 90 || //Read capital letters
                key.KeyChar >= 97 && key.KeyChar <= 122 || //Read lower letters
                key.Key == ConsoleKey.Spacebar)
            {
                Console.Write(key.KeyChar);
                if(Console.CursorLeft > outputString.Count)
                {
                    outputString.Add(' ');
                }
                outputString[Console.CursorLeft - 1] = key.KeyChar;
            }
            //This will remove character
            else if (key.Key == ConsoleKey.Backspace && Console.CursorLeft > 1)
            {
                ClearCurrentConsoleLine();
                outputString.RemoveAt(Console.CursorLeft - 1);
                var currentLeft = Console.CursorLeft;
                Console.CursorLeft = 0;
                Console.Write(outputString.Select(x => x.ToString()).Aggregate((x,y) => x + y));
                Console.CursorLeft = currentLeft - 1;
            }
            //This ends input loop
            //You can add more keys to break current loop with OR condition
            else if (key.Key == ConsoleKey.Enter)
            {
                break;
            }
        }
        //Display result and wait for any key
        Console.WriteLine(outputString.Select(x => x.ToString()).Aggregate((x, y) => x + y));
        Console.ReadKey();
    }

    //Clears current console line and sets cursor at where it was before
    public static void ClearCurrentConsoleLine()
    {
        int currentLineCursorTop = Console.CursorTop;
        int currentLineCursorLeft = Console.CursorLeft;
        Console.SetCursorPosition(0, Console.CursorTop);
        Console.Write(new string(' ', Console.WindowWidth));
        Console.SetCursorPosition(currentLineCursorLeft, currentLineCursorTop);
    }

Answer 2

您可以为此使用Console.CursorLeft = 0;。与Console.SetCursorPosition 相比的优势在于，您不必计算 y 坐标，因此光标停留在当前行。

我想为此做一个例子（在这两种情况下，我们都希望光标移动到行首）：

Console.SetCursorPosition(0, Console.CursorTop); //With SetCursorPosition
Console.CursorLeft = 0; //With CursorLeft

但是，我认为没有一种优雅的方式可以让用户删除程序编写的字符。您仍然可以不断检查用户是否按下 Backshift，然后删除最后一个字符并将光标向后移动，而您必须异步检查哪些不会产生好的解决方案。