Program window doesn't show up - c++

Question

I'm starting programming in C++ and want to start making applications with graphics and user interface.
I've watched many tutorials on the subject,
and have finished the first part of the tutorial
but the window refused to pop up, and I know that it's working because there are no errors,
and I can see it running in task manager.
Please help.
Hear is the code:
#include <Windows.h>
bool running = true;
LRESULT CALLBACK windows_callback(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
LRESULT result = 0;
switch (uMsg) {
case WM_CLOSE:
case WM_DESTROY: {
running = false;
}break;
default: {
result = DefWindowProc(hwnd, uMsg, wParam, lParam);
}
}
return result;
}
int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd) {
//compile window
WNDCLASS window_class = {};
window_class.style = CS_HREDRAW | CS_VREDRAW;
window_class.lpszClassName = 0;
window_class.lpfnWndProc = windows_callback;
//register clases
RegisterClass(&window_class);
// create window
HWND window = CreateWindowA(0, "game stuff", WS_OVERLAPPEDWINDOW | WS_VISIBLE, CW_USEDEFAULT, CW_USEDEFAULT, 720, 360, 0, 0, hInstance, 0); {
while (running) {
// input
// simulate
MSG mesage;
while (PeekMessage(&mesage, window, 0, 0, PM_REMOVE)) {
TranslateMessage(&mesage);
DispatchMessage(&mesage);
}
// render
}
};
}

Answer 1

window refused to pop up, and I know that it's working because there
are no errors, and I can see it running in task manager.
You don't check the error for RegisterClass and CreateWindowA functions calls.
Check the return value of RegisterClass() you will find that the return value is zero, that indicates failure. To get extended error information, call GetLastError.
CreateWindowA() also fails, the return value is NULL. To get extended error information, call GetLastError.
If you use ANSI version of these functions, change WNDCLASS to WNDCLASSA, RegisterClass to RegisterClassA.
You missed class name in both two functions. The following is an example based on your presented code to make the window show up. You can have a try.
CHAR clsName[] = "test";
WNDCLASSA window_class = {};
window_class.style = CS_HREDRAW | CS_VREDRAW;
window_class.lpszClassName = clsName;
window_class.lpfnWndProc = windows_callback;
//register clases
ATOM atom = RegisterClassA(&window_class);
if (0 == atom)
{
DWORD err = GetLastError();
return 0;
}
// create window
HWND window = CreateWindowA(clsName, "game stuff", WS_OVERLAPPEDWINDOW | WS_VISIBLE, CW_USEDEFAULT, CW_USEDEFAULT, 720, 360, 0, 0, hInstance, 0);
if (NULL == window)
{
DWORD err = GetLastError();
return 0;
}
More references: "Your First Windows Program", "Unicode in the Windows API".
Update:
why does it have a Chinese name (window's name displays unexecpted)
For using above sample code to display window's name expected you can change project setting to "Use Multi-Byte Character Set" like this:
Or you can use UNICODE APIs (RegisterClassW and CreateWindowW) with project setting "Use Unicode Character Set".
Or you can use the macros like RegisterClassEx and CreateWindowEx, it will choose UNICODE or ASCII version API along with your project setting automatically.