Winapi Window in c not responding - c

Question

I've been trying to make a simple window using WinAPI, it compiles and links with some warnings, when I open the program the window shows up, but when I try to interact with it, a windows warning sound is played and it doesn't allow me to use the window, not even close it, I have to use task manager.
To compile it I'm using Microsoft's "cl.exe" with the command line:
cl /c window.c
and the warnings are:
window.c(39): warning C4133: 'function': incompatible types, from 'LPSTR' to 'HINSTANCE'
window.c(40): warning C4133: 'function': incompatible types, from 'LPSTR' to 'HINSTANCE'
window.c(41): warning C4047: '=': 'HBRUSH' differs in levels of indirection from 'int'
To link I use crinkler with the commandline:
crinkler /NODEFAULTLIB /ENTRY:main /SUSBYSTEM:WINDOWS /TINYHEADER /TINYIMPORT /OUT:c.exe window.obj kernel32.lib user32.lib
and the warning is:
: warning LNK: Entry point not at start of section, jump necessary
The code I'm using is:
#include <windows.h>
#define WINDOW_STYLE WS_VISIBLE+WS_OVERLAPPEDWINDOW-WS_THICKFRAME-WS_MAXIMIZE
#define WINDOW_WIDTH 640
#define WINDOW_HEIGHT 480
static const char* window_name = "My Window";
RECT window_rect = {0, 0, WINDOW_HEIGHT, WINDOW_WIDTH};
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch(uMsg)
{
case WM_CLOSE:
PostQuitMessage(0);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
}
return DefWindowProcA(hwnd, uMsg, wParam, lParam);
}
int main()
{
int ret = 0;
HMODULE instance = GetModuleHandleA(NULL);
AdjustWindowRect(&window_rect, WINDOW_STYLE, FALSE);
WNDCLASSEXA window_class;
window_class.cbSize = 48;
window_class.style = CS_OWNDC|CS_HREDRAW|CS_VREDRAW;
window_class.lpfnWndProc = WindowProc;
window_class.cbClsExtra = 0;
window_class.cbWndExtra = 0;
window_class.hInstance = instance;
window_class.hIcon = LoadIconA(IDI_APPLICATION, 0);
window_class.hCursor = LoadCursorA(IDI_APPLICATION, 0);
window_class.hbrBackground = COLOR_WINDOW;
window_class.lpszMenuName = 0;
window_class.lpszClassName = window_name;
window_class.hIconSm = 0;
if (RegisterClassExA(&window_class)) {
HWND window = CreateWindowExA(
0,
window_name,
window_name,
WINDOW_STYLE,
CW_USEDEFAULT,
CW_USEDEFAULT,
window_rect.right - window_rect.left,
window_rect.bottom - window_rect.top,
0,
0,
instance,
NULL);
ShowWindow(window, SW_SHOW);
UpdateWindow(window);
MSG msg;
while(1)
{
if (PeekMessageA(&msg, 0, 0, 0, PM_REMOVE)) {
if (msg.message == WM_QUIT) {
ExitProcess(0);
break;
} else {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
}
} else {
ret = 1;
}
ExitProcess(0);
return ret;
}
Does anybody know how to fix it? Thanks.

Answer 1

The following line doesn't do what you think it does:
#define WINDOW_STYLE WS_VISIBLE+WS_OVERLAPPEDWINDOW-WS_THICKFRAME-WS_MAXIMIZE
While somewhat common, and occasionally even producing the correct value, it is a very brittle way to implement bit manipulations. In this particular case, the expression expands to:
0x10000000L + 0x00CF0000L - 0x00040000L - 0x01000000L
This produces the value 0xFFCB0000L1 (due to accidentally using WS_MAXIMIZE instead of WS_MAXIMIZEBOX). This translates to a window with the following styles:
WS_POPUP
WS_CHILD (note, that this is already mutually exclusive with WS_POPUP)
WS_ICONIC
WS_VISIBLE
WS_DISABLED
...
As documented:
WS_DISABLED: The window is initially disabled. A disabled window cannot receive input from the user. To change this after a window has been created, use the EnableWindow function.
That explains why you cannot interact with your window. The fix is simple: Use bitwise operators for bit manipulations instead of arithmetic operators:
#define WINDOW_STYLE (WS_VISIBLE | WS_OVERLAPPEDWINDOW & ~WS_THICKFRAME & ~WS_MAXIMIZE)
1 Leaving the fact, that the behavior for signed overflow is undefined aside.