如何使用C ++编写多个GetAsyncKeyState

Question

My problem is where can I add this line of code:

if( GetKeyState(VK_F2) & 0x8000 )

I tried in different ways, but when I compile and run it and press the F1 or F2 key it executes all the functions. I want to call the F1 key functions when the key is pressed and F2 key when it is pressed. I am using Visual Studio 2010 Express.

Here is my code:

switch(uMsg)
{
case WM_INITDIALOG:
    {
        // do something here
        break;
    }
case WM_TIMER:
    {
        if( GetKeyState(VK_F1) & 0x8000 )

        if( GetKeyState(VK_F2) & 0x8000 )

        {

            // do something here

        }
        break;
    }
case WM_CLOSE:
    {
           // do something here
    }
}
return 0;

Answer 1

SOLVED:) well my problem is solved after trying for sometime finally i got it the problem was that little "break;" statement please look at the code its working flawless. Thank you so very much for your time and help appreciated

case WM_TIMER:
    {
        if(GetKeyState(VK_F1) & 0x8000 )
    {
        MessageBoxA (NULL, TEXT ("This is a call from F1 key!"), TEXT("Test F1 key"), MB_OK );
    }

        //break; << this was the one that was giving me the problem 

         if(GetKeyState(VK_F2) & 0x8000 )
    {
        MessageBoxA (NULL, TEXT ("This is a call from F2 key!"), TEXT("Test F2 key"), MB_OK );
    }

        //if(GetKeyState(VK_F3) & 0x8000 ) << i can add multi VK_ keys here

        break; // << should be here
    }
case WM_CLOSE:

Answer 2

A couple points:

1. Are you sure you want to poll like this? Maybe you want to be responding to notifications when the user presses these keys (WM_KEYDOWN for example) instead of polling periodically? Your code has the problem that it can easily miss if you press & release F1 between WM_TIMER s.
2. You should probably be using GetKeyState , as Joachim Pileborg says. GetAsyncKeyState works on the state of the keyboard at the time of the call; GetKeyState works on the state of the keyboard when the current message was sent. This tends to keep things more tightly synchronized. That said, if you're polling in WM_TIMER , it probably doesn't matter so much.
3. You are only checking if the return value is non-zero, which is not how this function works. The return value is a bitmask. From the documentation:

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.

Thus, to check for F1 :

if( GetKeyState(VK_F1) & 0x8000 )
{
    ...
}