Win32 window - no close message - c++

Question

I am currently making a small win32 window wrapper class, but I have a few problem.
If I hit the close(X) button of the window the window closes immediately without sending a quit or destroy message, so I can't for example prevent the window to close or save something before closing the window.
And the second problem/question is,
If I use this small code to use the window, the computer cpu gets strongly used.
But its only a small window.
How I can change/fix this?
int main()
{
glwCreate();
while(true/*Later here comes a method that checks, wether window close is requested*/)
{
glwUpdate();
}
glwDestroy();
return 0;
}
-
#include "glw.h"
#include <windows.h>
#include <iostream>
HINSTANCE instanceHandle;
WNDCLASSEX windowClass;
HWND windowHandle;
LRESULT CALLBACK WindowMessageHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
std::cout<<uMsg<<'\n';
switch(uMsg)
{
case WM_QUIT:
{
std::cout<<"QUIT\n";
return 0;
}
case WM_DESTROY:
{
std::cout<<"DESTROY\n";
return 0;
}
}
return (DefWindowProc(hWnd, uMsg, wParam, lParam));
}
void glwCreate()
{
instanceHandle = GetModuleHandle(0);
windowClass.cbSize = sizeof(WNDCLASSEX);
windowClass.style = CS_HREDRAW | CS_VREDRAW;
windowClass.lpfnWndProc = WindowMessageHandler;
windowClass.cbClsExtra = 0;
windowClass.cbWndExtra = 0;
windowClass.hInstance = instanceHandle;
windowClass.hCursor = LoadCursor(0,IDC_ARROW);
windowClass.hIcon = LoadIcon(0, IDI_APPLICATION);
windowClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
windowClass.lpszClassName = "atomus_window_class";
windowClass.lpszMenuName = "menu_name";
windowClass.hIconSm = LoadIcon(0, IDI_APPLICATION);
RegisterClassEx(&windowClass);
windowHandle = CreateWindowEx( 0,
"atomus_window_class",
"atomus title",
WS_OVERLAPPEDWINDOW,
0,
0,
CW_USEDEFAULT,
CW_USEDEFAULT,
0,
0,
instanceHandle,
0);
ShowWindow(windowHandle, SW_SHOW);
}
void glwDestroy()
{
DestroyWindow(windowHandle);
windowHandle = 0;
UnregisterClass(windowClass.lpszClassName, instanceHandle);
}
void glwUpdate()
{
MSG message;
while (PeekMessage (&message, 0, 0, 0, PM_REMOVE) > 0) //Or use an if statement
{
TranslateMessage (&message);
DispatchMessage (&message);
}
}

Answer 1

If you add handling for WM_CLOSE you get to control whether your window closes or not. By not providing your own handling for that message you get the default from DefWindowProc which is to destroy your window.