The lpMsg
argument to GetMessage is not allowed to be NULL (0).
This call:
while (GetMessage(0, hwnd, 0, 0))
Needs to be:
while (GetMessage(&msg, hwnd, 0, 0))
Vra
Problem Event Name: APPCRASH
Application Name: program.exe
Application Version: 0.0.0.0
Application Timestamp: 537374b6
Fault Module Name: USER32.dll
Fault Module Version: 6.3.9600.16384
Fault Module Timestamp: 52157ca5
Exception Code: c0000005
Exception Offset: 0000949d
OS Version: 6.3.9600.2.0.0.256.48
Locale ID: 1049
Additional Information 1: 5861
Additional Information 2: 5861822e1919d7c014bbb064c64908b2
Additional Information 3: 3a20
Additional Information 4: 3a20a93c34687143a5bf7d33f1cf3ccc
Im trying to make C++ winapi program, the its only function is to draw a window with a button that toggles cursor move and click, but right after window is shown, the app crashes before able to do something. In window procedure i have only WM_COMMAND, WM_DESTROY and default return DefWindowProc() cases. The WinMain function code:
WNDCLASSEX wcx;
int X, Y;
MSG msg;
RECT srect;
GetWindowRect(GetDesktopWindow(), &srect);
X = srect.right;
Y = srect.bottom;
wcx.cbSize = sizeof(WNDCLASSEX);
wcx.style = CS_HREDRAW | CS_VREDRAW | CS_DROPSHADOW;
wcx.lpfnWndProc = MainProc;
wcx.cbClsExtra = 0;
wcx.cbWndExtra = 0;
wcx.hInstance = hinst;
wcx.hIcon = 0;
wcx.hCursor = 0;
wcx.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wcx.lpszMenuName = 0;
wcx.lpszClassName = L"wcname";
wcx.hIconSm = 0;
if (!RegisterClassEx(&wcx)){
MessageBox(0, L".", L"RegisterClass failed", 0);
return 1;
}
hwnd = CreateWindowEx(
0,
L"wcname",
L"off",
WS_OVERLAPPEDWINDOW,
X / 2 - 112,
Y / 2 - 40,
224,
80,
0,
0,
hinst,
0
);
if (!hwnd){
MessageBox(0, L".", L"CreateWindow failed", 0);
return 1;
}
GetClientRect(hwnd, &srect);
X = srect.right;
Y = srect.bottom;
btn = CreateWindowEx(
0,
L"button",
L"Turn on",
WS_VISIBLE | WS_CHILD | BS_PUSHBUTTON,
0, 0,
X, Y,
hwnd,
(HMENU)BTN,
hinst,
0
);
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
while (GetMessage(0, hwnd, 0, 0)){
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return 0;
The HWNDs are global variables, BTN and MAIN are macros.
Oplossing
The lpMsg
argument to GetMessage is not allowed to be NULL (0).
This call:
while (GetMessage(0, hwnd, 0, 0))
Needs to be:
while (GetMessage(&msg, hwnd, 0, 0))