Using GetKeyState()

Question

I would like to have a boolean event toggle when a key is pressed. Specifically, the 's' key. I have been pointed to the function GetKeyState(), which supposedly works under the Win32 API. I understand the ASCII code for the letter 's' is 115, and so my code is as follows:

if (GetKeyState(115) == 1)
{
<EVENT>
}

However, this does not work. Why? Here is the MSDN reference: http://msdn.microsoft.com/en-us/library/ms646301%28v=vs.85%29.aspx ... "If the low-order bit is 1, the key is toggled"

Answer 1

From what I understand you need to do:

if( GetKeyState(115) & 0x8000 )
{
    <EVENT>
}

The highest bit tells if key is pressed. The lowest tells if key is toggled (like, if caps lock is turned on).

Answer 2

Since SHORT is signed, high-order bit equals sign bit.

Therefore to test if a given key is pressed, simply test if the value returned by GetKeyState() is negative:

if (GetKeyState('S') < 0) {
    // The S key is down.
} else {
    // The S key is up.
}

Besides, 115 is ASCII code for 's'. I believe, you should use capital case 83 to test the 'S' key.