Console.ReadKey Method ()

 

Obtains the next character or function key pressed by the user. The pressed key is displayed in the console window.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, UI = true)]
public static ConsoleKeyInfo ReadKey()

Return Value

Type: System.ConsoleKeyInfo

An object that describes the ConsoleKey constant and Unicode character, if any, that correspond to the pressed console key. The ConsoleKeyInfo object also describes, in a bitwise combination of ConsoleModifiers values, whether one or more Shift, Alt, or Ctrl modifier keys was pressed simultaneously with the console key.

Exception Condition
InvalidOperationException

The In property is redirected from some stream other than the console.

The ReadKey method waits, that is, blocks on the thread issuing the ReadKey method, until a character or function key is pressed. A character or function key can be pressed in combination with one or more Alt, Ctrl, or Shift modifier keys. However, pressing a modifier key by itself will not cause the ReadKey method to return.

Depending on your application, you might want to use the ReadKey method in conjunction with the KeyAvailable property.

The ReadKey method reads from the keyboard even if the standard input is redirected to a file with the SetIn method.

One of the most common uses of the ReadKey() method is to halt program execution until the user presses a key and the app either terminates or displays an additional window of information. The following example uses the ReadKey() method to wait for the user to press the Enter key before terminating the app.

using System;

public class Example
{
   public static void Main()
   {
      DateTime dat = DateTime.Now;
      Console.WriteLine("The time: {0:d} at {0:t}", dat);
      TimeZoneInfo tz = TimeZoneInfo.Local;
      Console.WriteLine("The time zone: {0}\n", 
                        tz.IsDaylightSavingTime(dat) ?
                           tz.DaylightName : tz.StandardName);
      Console.Write("Press <Enter> to exit... ");
      while (Console.ReadKey().Key != ConsoleKey.Enter) {}
   }
}
// The example displays output like the following:
//     The time: 11/11/2015 at 4:02 PM:
//     The time zone: Pacific Standard Time

Note that this overload of the ReadKey method by default echoes any displayable keys that the user presses to the console. To suppress them, call the ReadKey method with an intercept argument of true.

The following example uses the ReadKey() method to display information about which key the user pressed..

using System;

class Example 
{
   public static void Main() 
   {
      ConsoleKeyInfo cki;
      // Prevent example from ending if CTL+C is pressed.
      Console.TreatControlCAsInput = true;

      Console.WriteLine("Press any combination of CTL, ALT, and SHIFT, and a console key.");
      Console.WriteLine("Press the Escape (Esc) key to quit: \n");
      do 
      {
         cki = Console.ReadKey();
         Console.Write(" --- You pressed ");
         if((cki.Modifiers & ConsoleModifiers.Alt) != 0) Console.Write("ALT+");
         if((cki.Modifiers & ConsoleModifiers.Shift) != 0) Console.Write("SHIFT+");
         if((cki.Modifiers & ConsoleModifiers.Control) != 0) Console.Write("CTL+");
         Console.WriteLine(cki.Key.ToString());
       } while (cki.Key != ConsoleKey.Escape);
    }
}
// This example displays output similar to the following:
//       Press any combination of CTL, ALT, and SHIFT, and a console key.
//       Press the Escape (Esc) key to quit:
//       
//       a --- You pressed A 
//       k --- You pressed ALT+K 
//       ► --- You pressed CTL+P 
//         --- You pressed RightArrow 
//       R --- You pressed SHIFT+R 
//                --- You pressed CTL+I 
//       j --- You pressed ALT+J 
//       O --- You pressed SHIFT+O 
//       § --- You pressed CTL+U 

.NET Framework
Available since 2.0
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