Simple WIN32 Window

#include<Windows.h>

#define WIN32_LEAN_AND_MEAN //speeds up compiler

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) { //Window message processing
    switch (msg)
    {
    case WM_CLOSE:
        DestroyWindow(hwnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

int WinMain(_In_ HINSTANCE hInstance, _In_opt_  HINSTANCE hPrevInstance, _In_ LPSTR lpCmdLine, _In_ int nCmdShow){ //Entry Point

    //(Optional stuff, does nothing)
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);
    UNREFERENCED_PARAMETER(nCmdShow);

    WNDCLASS window; //Create window class

    //Define window class
    window.cbClsExtra = NULL;
    window.cbWndExtra = NULL;
    window.hbrBackground = (HBRUSH)COLOR_WINDOW;
    window.hCursor = LoadCursor(NULL, IDC_ARROW);
    window.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    window.hInstance = hInstance;
    window.lpfnWndProc = WndProc;
    window.lpszClassName = "just_window";
    window.lpszMenuName = nullptr;
    window.style = NULL;

    RegisterClass(&window); //Register the defined window class

    CreateWindow("just_window","Test", WS_VISIBLE | WS_SYSMENU,0,0,500,500,nullptr,nullptr,hInstance,nullptr); //Create the defined window

    MSG msg; //Create message class

    while (GetMessage(&msg, NULL, 0, 0)) { //Message loop, get message
        TranslateMessage(&msg); //Translate Message
        DispatchMessage(&msg); //Send message to WndProc
    }

    return (int) msg.wParam;
}