#include <windows.h>
#include <tchar.h>
 
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;
    LPCTSTR lpszMessage = _T("Hello, Win32 GUI World!");
 
    switch (message)
    {
    case WM_PAINT:
        hdc = BeginPaint( hWnd, &ps );
        TextOut( hdc, 0, 0, lpszMessage, lstrlen(lpszMessage) );
        EndPaint( hWnd, &ps );
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
        break;
    }
 
    return 0;
}
 
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    LPCTSTR lpszClassName = _T("helloWindow");
    LPCTSTR lpszWindowName = _T("Hello, World!");
    WNDCLASSEX wcex;
    HWND hWnd;
    MSG msg;
 
    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = hInstance;
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
    wcex.lpszClassName  = lpszClassName;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
 
    RegisterClassEx(&wcex);
    hWnd = CreateWindow(
        lpszClassName,
        lpszWindowName,
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 640, 480,
        NULL, NULL, hInstance, NULL
    );
 
    ShowWindow(hWnd, SW_SHOWDEFAULT);
    UpdateWindow(hWnd);
 
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
 
    return (int)msg.wParam;
}

C:¥> cl hello.c /link user32.lib gdi32.lib /SUBSYSTEM:WINDOWS

+------------------------------------------+
|Hello, World!                    [_][~][X]|
+------------------------------------------+
|Hello, Win32 GUI World!                   |
|                                          |
|                                          |
|                                          |
|                                          |
|                                          |
|                                          |
|                                          |
|                                          |
|                                          |
+------------------------------------------+