Console.ReadKey canceling

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How to add a Timeout to Console.ReadLine()?

If I have a Console.ReadKey(), It makes the whole program stuck, how can I make it so that it will read a key for 1 second, and if a key is not read, something else would be set.

As sixlettervariables mentioned, you need to only ask one question at a time unless they are two parts of the same question. These are not. You should **edit** your question to remove one of your questions and rename the title. — BlackVegetable, Jan 17 '13 at 17:51
similar to http://stackoverflow.com/questions/57615/how-to-add-a-timeout-to-console-readline — Nasmi Sabeer, Jan 17 '13 at 17:57
I am only a begginer in c#, so the code given to the guy in the link you gave me made 0 sense to me. Is there just a simple code that will wait make the Console.ReadKey command cancel out after a set amount of time? — user1823701, Jan 17 '13 at 18:10
@user1823701 Even if you are a beginner you should learn how to do things correctly. if there is some aspect of the code you don't understand search msdn and other sites for documentation and examples. It's the only way to learn. — Tobsey, Jan 18 '13 at 08:56

Olivier Jacot-Descombes · Answer 1 · 2013-06-02T15:09:51.663

12

The console has a property KeyAvailable. But your desired functionality (timeout) is not available. You could write your own function

private static ConsoleKeyInfo WaitForKey(int ms)
{
    int delay = 0;
    while (delay < ms) {
        if (Console.KeyAvailable) {
            return Console.ReadKey();
        }
        Thread.Sleep(50);
        delay += 50;
    }
    return new ConsoleKeyInfo((char)0, (ConsoleKey)0, false, false, false);
}

This function loops until the desired time in milliseconds has elapsed or a key has been pressed. It checks to see whether a key is available before it calls Console.ReadKey();. The check Console.KeyAvailable continues immediately, whether a key is available or not. It returns true if a key has been pressed and is ready to be read by ReadKey and false otherwise. If no key is available the function sleeps for 50 ms until it performs the next loop. This is better than looping without sleeping, because that would give you 100% CPU usage (on one core).

The function returns a ConsoleKeyInfo as ReadKey would, in case you want to know which key the user has pressed. The last line creates an empty ConsoleKeyInfo (see ConsoleKeyInfo Structure and ConsoleKeyInfo Constructor). It allows you to test whether the user pressed a key or whether the function timed out.

if (WaitForKey(1000).KeyChar == (char)0) {
    // The function timed out
} else {
    // The user pressed a key
}

edited Jun 02 '13 at 15:09

answered Jan 17 '13 at 18:13

Olivier Jacot-Descombes

104,806
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Well, this it does the job, mind explaining how this works? – user1823701 Jan 17 '13 at 18:25
1

Added explanation. (Sorry, I thought it was obvious). – Olivier Jacot-Descombes Jan 17 '13 at 18:34
How does the Console.KeyAvailable works? and what does the long line in the end means (and what is that false,false,false?)? – user1823701 Jan 17 '13 at 18:34
Added some more explanations. – Olivier Jacot-Descombes Jan 17 '13 at 18:47
I'm messing with the Console.KeyAvailable, How can I reset it so it wont be true forever? – user1823701 Jan 17 '13 at 19:12
if `KeyAvailable` is `true` you can call `ReadKey`. `ReadKey` sets `KeyAvailable` to `false`. If the user pressed more than one key, you could add this after the call to `WaitForKey`: `while (Console.KeyAvailable) { ReadKey(); }` – Olivier Jacot-Descombes Jan 17 '13 at 19:21
Or you could do this: `while (WaitForKey(1000).KeyChar != (char)0) { }`. This waits one more second every time the user presses a key until the user does not press any key for one second or more. – Olivier Jacot-Descombes Jan 17 '13 at 19:31
No idea KeyAvailable even existed. Thank you :) – andygjp Jul 06 '17 at 17:07

score 6 · Answer 2 · answered Jan 17 '13 at 18:22

6

static ConsoleKeyInfo? MyReadKey()
{
    var task = Task.Run(() => Console.ReadKey(true));
    bool read = task.Wait(1000);
    if (read) return task.Result;
    return null;
}

var key = MyReadKey();
if (key == null)
{
    Console.WriteLine("NULL");
}
else
{
    Console.WriteLine(key.Value.Key);
}

answered Jan 17 '13 at 18:22

I4V

34,891
6
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The Task is never disposed which i think leads to unusable ThreadPool threads... – Daniel Bişar Apr 10 '20 at 20:02

score 1 · Answer 3 · answered Jan 17 '13 at 18:08

Do you mean something like this?

    Console.WriteLine("Waiting for input for 10 seconds...");

    DateTime start = DateTime.Now;

    bool gotKey = false;

    while ((DateTime.Now - start).TotalSeconds < 10)                
    {
        if (Console.KeyAvailable)
        {
            gotKey = true;
            break;
        }            
    }

    if (gotKey)
    {
        string s = Console.ReadLine();
    }
    else
        Console.WriteLine("Timed out");

Console.ReadKey canceling

3 Answers3

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