Applies to: desktop apps only
Retrieves the status of the specified virtual key. The status specifies whether the key is up, down, or toggled (on, off—alternating each time the key is pressed).
Syntax
SHORT WINAPI GetKeyState( __in int nVirtKey );
Parameters
- nVirtKey [in]
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Type: int
A virtual key. If the desired virtual key is a letter or digit (A through Z, a through z, or 0 through 9), nVirtKey must be set to the ASCII value of that character. For other keys, it must be a virtual-key code.
If a non-English keyboard layout is used, virtual keys with values in the range ASCII A through Z and 0 through 9 are used to specify most of the character keys. For example, for the German keyboard layout, the virtual key of value ASCII O (0x4F) refers to the "o" key, whereas VK_OEM_1 refers to the "o with umlaut" key.
Return value
Type: SHORT
The return value specifies the status of the specified virtual key, as follows:
- If the high-order bit is 1, the key is down; otherwise, it is up.
- If the low-order bit is 1, the key is toggled. A key, such as the CAPS LOCK key, is toggled if it is turned on. The key is off and untoggled if the low-order bit is 0. A toggle key's indicator light (if any) on the keyboard will be on when the key is toggled, and off when the key is untoggled.
Remarks
The key status returned from this function changes as a thread reads key messages from its message queue. The status does not reflect the interrupt-level state associated with the hardware. Use the GetAsyncKeyState function to retrieve that information.
An application calls GetKeyState in response to a keyboard-input message. This function retrieves the state of the key when the input message was generated.
To retrieve state information for all the virtual keys, use the GetKeyboardState function.
An application can use the virtual key code constants VK_SHIFT, VK_CONTROL, and VK_MENU as values for the nVirtKey parameter. This gives the status of the SHIFT, CTRL, or ALT keys without distinguishing between left and right. An application can also use the following virtual-key code constants as values for nVirtKey to distinguish between the left and right instances of those keys:
- VK_LSHIFT
- VK_RSHIFT
- VK_LCONTROL
- VK_RCONTROL
- VK_LMENU
- VK_RMENU
These left- and right-distinguishing constants are available to an application only through the GetKeyboardState, SetKeyboardState, GetAsyncKeyState, GetKeyState, and MapVirtualKey functions.
Examples
For an example, see Displaying Keyboard Input.
Requirements
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Minimum supported client | Windows 2000 Professional |
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Minimum supported server | Windows 2000 Server |
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Header |
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Library |
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DLL |
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See also
- Reference
- GetAsyncKeyState
- GetKeyboardState
- MapVirtualKey
- SetKeyboardState
- Conceptual
- Keyboard Input
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Build date: 3/6/2012
0 if the key is neither down nor toggled,
-127 if the key is down but not toggled,
1 if the key is toggled but up, and
-128 if the key is both toggled and down.
[DllImport("user32.dll", CharSet=CharSet.Auto, ExactSpelling=true)]
internal static extern short GetKeyState(int virtualKeyCode);
<DllImport("user32.dll", CharSet:=CharSet.Auto, ExactSpelling:=True)> _
Public Shared Function GetKeyState(ByVal virtualKeyCode As Integer) As Short
End Function
Here's how to P\Invoke in F#:
#light open System.Runtime.InteropServices
/// Keyboard functions
module (*internal*) Keyboard =
/// Determine the state of a particular key on the keyboard.
/// See Win32 API
[<DllImport("User32.dll")>]
let GetKeyState(key:int) : int16 = failwith ""