how-to-determine-which-modifier-key-was-pressed.md

title	description	ms.date	dev_langs	helpviewer_keywords	ms.assetid
How to: Determine Which Modifier Key Was Pressed	Learn how to determine which modifier key has been pressed when you create an application that accepts user keystrokes.	03/30/2017	csharp vb cpp	keyboard input shift keys events [Windows Forms], mouse Keys.ControlKey enumeration member keys [Windows Forms], control keys user input [Windows Forms], checking for keyboard keys [Windows Forms], determining last pressed keys [Windows Forms], shift keys keys [Windows Forms], modifier keys control keys keys [Windows Forms], alt keys alt keys Keys.Shift enumeration member events [Windows Forms], keyboard keyboards [Windows Forms], keyboard input Keys.Alt enumeration member modifier keys	1e184048-0ae3-4067-a200-d4ba31dbc2cb

How to: Determine Which Modifier Key Was Pressed

When you create an application that accepts the user's keystrokes, you may also want to monitor for modifier keys such as the SHIFT, ALT, and CTRL keys. When a modifier key is pressed in combination with other keys, or with mouse clicks, your application can respond appropriately. For example, if the letter S is pressed, this may simply cause an "s" to appear on the screen, but if the keys CTRL+S are pressed, the current document may be saved. If you handle the xref:System.Windows.Forms.Control.KeyDown event, the xref:System.Windows.Forms.KeyEventArgs.Modifiers%2A property of the xref:System.Windows.Forms.KeyEventArgs received by the event handler specifies which modifier keys are pressed. Alternatively, the xref:System.Windows.Forms.KeyEventArgs.KeyData%2A property of xref:System.Windows.Forms.KeyEventArgs specifies the character that was pressed as well as any modifier keys combined with a bitwise OR. However, if you are handling the xref:System.Windows.Forms.Control.KeyPress event or a mouse event, the event handler does not receive this information. In this case, you must use the xref:System.Windows.Forms.Control.ModifierKeys%2A property of the xref:System.Windows.Forms.Control class. In either case, you must perform a bitwise AND of the appropriate xref:System.Windows.Forms.Keys value and the value you are testing. The xref:System.Windows.Forms.Keys enumeration offers variations of each modifier key, so it is important that you perform the bitwise AND with the correct value. For example, the SHIFT key is represented by xref:System.Windows.Forms.Keys.Shift, xref:System.Windows.Forms.Keys.ShiftKey, xref:System.Windows.Forms.Keys.RShiftKey and xref:System.Windows.Forms.Keys.LShiftKey The correct value to test SHIFT as a modifier key is xref:System.Windows.Forms.Keys.Shift. Similarly, to test for CTRL and ALT as modifiers you should use the xref:System.Windows.Forms.Keys.Control and xref:System.Windows.Forms.Keys.Alt values, respectively.

Note

Visual Basic programmers can also access key information through the xref:Microsoft.VisualBasic.Devices.Computer.Keyboard%2A property

To determine which modifier key was pressed

• Use the bitwise AND operator with the xref:System.Windows.Forms.Control.ModifierKeys%2A property and a value of the xref:System.Windows.Forms.Keys enumeration to determine whether a particular modifier key is pressed. The following code example shows how to determine whether the SHIFT key is pressed within a xref:System.Windows.Forms.Control.KeyPress event handler.

  [!code-cppSystem.Windows.Forms.DetermineModifierKey#5] [!code-csharpSystem.Windows.Forms.DetermineModifierKey#5] [!code-vbSystem.Windows.Forms.DetermineModifierKey#5]

See also

• xref:System.Windows.Forms.Keys
• xref:System.Windows.Forms.Control.ModifierKeys%2A
• Keyboard Input in a Windows Forms Application
• How to: Determine If CapsLock is On in Visual Basic