Console.KeyAvailable Propiedad

Definición

Espacio de nombres:

System

Ensamblados:

netstandard.dll, System.Console.dll

Source:

Console.cs

Obtiene un valor que indica si hay una pulsación de tecla disponible en el flujo de entrada.

public:
 static property bool KeyAvailable { bool get(); };

public static bool KeyAvailable { get; }

static member KeyAvailable : bool

Public Shared ReadOnly Property KeyAvailable As Boolean

Valor de propiedad

Boolean

true si hay disponible una pulsación de tecla; de lo contrario, false.

Excepciones

IOException

Error de E/S.

InvalidOperationException

La entrada estándar se redirige a un archivo en lugar del teclado.

Ejemplos

En el ejemplo siguiente se muestra cómo usar la KeyAvailable propiedad para crear un bucle que se ejecuta hasta que se presiona una tecla.

using System;
using System.Threading;

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

       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)
               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:

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.
*/

open System
open System.Threading

let mutable cki = Unchecked.defaultof<ConsoleKeyInfo>

while cki.Key <> ConsoleKey.X do
    printfn "\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 not Console.KeyAvailable do
        Thread.Sleep 250 // Loop until input is entered.

    cki <- Console.ReadKey true
    printfn $"You pressed the '{cki.Key}' key."


// This example produces results similar to the following:
//
// 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.

Imports System.Threading

Class Sample
   Public Shared Sub Main()
      Dim cki As ConsoleKeyInfo
      
      Do
         Console.WriteLine(vbCrLf & "Press 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.
         End While
         cki = Console.ReadKey(True)
         Console.WriteLine("You pressed the '{0}' key.", cki.Key)
      Loop While cki.Key <> ConsoleKey.X
   End Sub 
End Class 
'This example produces results similar to the following:
'
'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.
'

Comentarios

El valor de la propiedad se devuelve inmediatamente; es decir, la propiedad no bloquea la KeyAvailable entrada hasta que haya disponible una tecla presionada.

Utilice la KeyAvailable propiedad junto con solo el ReadKey método , no con los Read métodos o ReadLine .