The GetKeyboardState function copies the status of the 256 virtual keys to the specified buffer.
BOOL GetKeyboardState(
PBYTE lpKeyState // pointer to array to receive status data
);
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
An application can call this function to retrieve the current status of all the virtual keys. The status changes as a thread removes keyboard messages from its message queue. The status does not change as keyboard messages are posted to the thread's message queue, nor does it change as keyboard messages are posted to or retrieved from message queues of other threads. (Exception: Threads that are connected via AttachThreadInput share the same keyboard state.)
When the function returns, each member of the array pointed to by the lpKeyState parameter contains status data for a virtual key. 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.
To retrieve status information for an individual key, use the GetKeyState function. To retrieve the current state for an individual key regardless of whether the corresponding keyboard message has been retrieved from the message queue, use the GetAsyncKeyState function
An application can use the virtual-key code constants VK_SHIFT, VK_CONTROL and VK_MENU as indices into the array pointed to by lpKeyState. 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 indices 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.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Keyboard Input Overview, Keyboard Input Functions, GetKeyState, GetAsyncKeyState, MapVirtualKey, SetKeyboardState