NET C# 控制台应用程序未正确检测按键

Question

I have a console program. Its purpose is to check if the keys F1-F2 is pressed in a loop and then send out a message if one of those keys is pressed but I cannot get it to work properly. The way I detect or listen for keys is if(Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.F2) . Console.ReadKey(true).Key == ConsoleKey.F2 Blocks the execution and waits for input so I have to put Console.KeyAvailable in front of it, so the loop can just continue and check if the next key is pressed. I did this in a while(true) loop, in Main() until I reached out to one of my friends who told me to put the whole thing in a standalone thread. I did just that which made almost no difference (besides some cleaner code).

I read about Keyboard.GetKeyStates(Key) method, but turns out this doesn't work in a C# NET Console app. Currently, the loop doesn't even want to go past checking if F1 is pressed unless I make another separate thread to check if F2 is pressed, which results in it still not working and having to spam the keys to get the if s to do anything in the first place.

Code:

class Program
    {
        public static void Main()
        {
            Thread ThreadObj = new Thread(F1); //Creating the Thread    
            ThreadObj.Start(); //Starting the Thread    

        }
        static void F1()
        {
            Console.WriteLine("Thread Started");
            while (true)
            {
                if (Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.F1)
                {
                    Console.WriteLine("F1");
                }
                if (Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.F2)
                {
                    Console.WriteLine("F2");
                }
                Thread.Sleep(10);
            }
        }
    }

Answer 1

Not sure why do you need threads here.

1. Run the while loop and check if there is KeyAvailable . Only if the key is available (a user pressed something), use the ReadKey function that blocks the thread.

2. Provide a key that breaks the loop (ESC in this case).

    static void Main(string[] args) { Console.WriteLine("Press ESC to quit."); ConsoleKey key; do { while (.Console.KeyAvailable) { // Do something } key = Console.ReadKey(true);Key. if(key == ConsoleKey;Escape) { break. } else if (key == ConsoleKey.F12 || key == ConsoleKey.F11) { Console;WriteLine("F12 or F11 pressed"); } } while (true); }

Answer 2

using System;

using System.Threading;

class Program

{

    public static void Main()

    {
        Thread ThreadObj = new Thread(F1); //Creating the Thread    
        ThreadObj.Start(); //Starting the Thread

    }
    static void F1()
    {
        Console.WriteLine("Thread Started");
        while (true)
        {
            if (Console.ReadKey(true).Key == ConsoleKey.F1)
            {
                Console.WriteLine("F1");
            }
            if (Console.ReadKey(true).Key == ConsoleKey.F2)
            {
                Console.WriteLine("F2");
            }
            Thread.Sleep(10);
        }
    }
}

Answer 3

A key point to understand is that ReadKey() consumes the keypress. So after checking for F1 in the first if statement, the KeyAvailable() call in the second if statement will return false and therefore you'll never detect anything but F1.

You want to wait until there is a key available, and then call ReadKey() ONCE, using that same return value in multiple checks:

        while (true)
        {

            // wait for a keypress
            while (!Console.KeyAvailable)
            {
                Thread.Sleep(100);
            }

            ConsoleKeyInfo cki = Console.ReadKey(true); // call ReadKey() once...

            // ...and use "cki" multiple times
            // (note there are no more ReadKey() calls below)
            if (cki.Key == ConsoleKey.F1)
            {
                Console.WriteLine("F1");
            }
            else if (cki.Key == ConsoleKey.F2)
            {
                Console.WriteLine("F2");
            }
        }