C++ Window with Button Click Event

Use the CreateWindow function to create a button control.

In the following C++ example, he BS_DEFPUSHBUTTON style specifies that a default push button should be created. Note that the size and position values must be specified because using CW_USEDEFAULT for a button sets the values to zero.

Code:

#include <windows.h>
#define IDB_BUT 100

LRESULT CALLBACK WindowFunc(HWND hWnd,UINT Message,WPARAM wParam,LPARAM lParam){
    switch(Message) {
        case WM_CREATE:
            CreateWindow("button", 
                "Say Hello", WS_VISIBLE | WS_CHILD, 
                100, 100, 120, 30, hWnd, (HMENU) IDB_BUT, 
                NULL, NULL
            );
            break;

        case WM_COMMAND:
            switch (HIWORD(wParam)) {
                case BN_CLICKED:
                    MessageBox(NULL, "Hello IDEA Developers", "Dialog Box", MB_OK);
                    break;

                default:
                    break;
            }
            break;
        case WM_PAINT: {
                PAINTSTRUCT ps;
                BeginPaint(hWnd, &ps);
                EndPaint(hWnd, &ps);
            }
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;

        default:
            return DefWindowProc(hWnd, Message, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hThisInst, HINSTANCE hPrevInst, LPSTR Args, int WinMode){
WNDCLASSEX WinClass = { 0 };
WinClass.cbSize        = sizeof(WNDCLASSEX);
WinClass.hInstance     = hThisInst;
WinClass.lpszClassName = "BUTEXP";
WinClass.lpfnWndProc   = WindowFunc;
WinClass.style         = 0;
WinClass.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
WinClass.hIconSm       = LoadIcon(NULL, IDI_WINLOGO);
WinClass.hCursor       = LoadCursor(NULL, IDC_ARROW);
WinClass.lpszMenuName  = NULL;
WinClass.cbClsExtra    = 0;
WinClass.cbWndExtra    = 0;

if (!RegisterClassEx(&WinClass)) {
            MessageBox(NULL, "Cannot register class", "Windows error", MB_OK);
            return 1;
}

HWND hWnd = CreateWindow(
                "BUTEXP", "IDEA Developers", 
                WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 
                CW_USEDEFAULT, 500, 400, NULL, 
                NULL, hThisInst, NULL
        );

if (!(hWnd)) {
            MessageBox(NULL, "Cannot create window", "Windows error", MB_OK);
            return 2;
}

ShowWindow(hWnd, WinMode);
UpdateWindow(hWnd);
MSG Message;

while (GetMessage(&Message, NULL, 0, 0) > 0){
            TranslateMessage(&Message);
            DispatchMessage(&Message);
}
return Message.wParam;
}