Export (0) Print
Expand All

Console.KeyAvailable Property

Gets a value indicating whether a key press is available in the input stream.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static bool KeyAvailable { get; }

Property Value

Type: System.Boolean
true if a key press is available; otherwise, false.

ExceptionCondition
IOException

An I/O error occurred.

InvalidOperationException

Standard input is redirected to a file instead of the keyboard.

The property value is returned immediately; that is, the KeyAvailable property does not block input until a key press is available.

Use the KeyAvailable property in conjunction with only the ReadKey method, not the Read or ReadLine methods.

The following example demonstrates how to use the KeyAvailable property to create a loop that runs until a key is pressed.


// This example demonstrates the Console.KeyAvailable property.
using System;
using System.Threading;

class Sample 
{
    public static void Main() 
    {
    ConsoleKeyInfo cki = new ConsoleKeyInfo();

    do {
        Console.WriteLine("\nPress a key to display; press the 'x' key to quit.");

// Your code could perform some useful task in the following loop. However, 
// for the sake of this example we'll merely pause for a quarter second.

        while (Console.KeyAvailable == false)
            Thread.Sleep(250); // Loop until input is entered.
        cki = Console.ReadKey(true);
        Console.WriteLine("You pressed the '{0}' key.", cki.Key);
        } while(cki.Key != ConsoleKey.X);
    }
}
/*
This example produces results similar to the following text:

Press a key to display; press the 'x' key to quit.
You pressed the 'H' key.

Press a key to display; press the 'x' key to quit.
You pressed the 'E' key.

Press a key to display; press the 'x' key to quit.
You pressed the 'PageUp' key.

Press a key to display; press the 'x' key to quit.
You pressed the 'DownArrow' key.

Press a key to display; press the 'x' key to quit.
You pressed the 'X' key.
*/


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Community Additions

ADD
Show:
© 2014 Microsoft