程序代码：

#include <windows.h>
#include <math.h>
#define  NUM  100

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int  WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
    static TCHAR szAppName[] =TEXT("拥抱世界");
    HWND      hwnd;
    MSG       msg;
    WNDCLASS  wndclass;

    wndclass.style = CS_HREDRAW || CS_VREDRAW;
    wndclass.lpfnWndProc = WndProc;
    wndclass.cbClsExtra = 0;
    wndclass.cbWndExtra = 0;
    wndclass.hInstance = hInstance;
    wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
    wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = szAppName;

    if(!RegisterClass(&wndclass))
    {
        MessageBox(NULL, TEXT("This program requires windows NT!"), szAppName, MB_ICONERROR);
        return 0;   
    }

    hwnd = CreateWindow(szAppName, TEXT("风光无限好"),  // CreateWindow下波浪线，是整个程序中唯一一处。
                        WS_OVERLAPPENDWINDOW,           /*但是编译出现错误提示是           error C2065: “WS_OVERLAPPENDWINDOW”: 未声明的标识符*/
                        CW_USEDEFAULT,
                        CW_USEDEFAULT,
                        CW_USEDEFAULT,
                        CW_USEDEFAULT,
                        NULL, NULL, hInstance, NULL);

    ShowWindow(hwnd, iCmdShow);
    UpdateWindow(hwnd);

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

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    HDC        hdc;
    int     i;
    PAINTSTRUCT ps;
    POINT   apt[NUM];
    RECT rect;

    switch(message)
    {
    case  WM_CREATE:
        PlaySound(TEXT("hellowin.wav"), NULL, SND_FILENAME | SND_ASYNC);
        return 0;
    case  WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        GetClientRect(hwnd, &rect);
        DrawText(hdc, TEXT("Hello, Windows program design!"), -1, &rect,
                 DT_SINGLELINE | DT_CENTER | DT_VCENTER);
        EndPaint(hwnd, &ps);
        return 0;
    case  WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}

程序代码：

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)     
{ 
    static int  cxClient, cyClient ;   //  是定义X Y坐标吗？
    HDC         hdc;      
    int         i ;       
    PAINTSTRUCT ps ;                    //  这个结构体指针有什么用？
    POINT       apt [NUM] ;             //  是放点的数组吧。     
    switch (message)      
    {      
       case   WM_SIZE:      
           cxClient = LOWORD (lParam) ; // 这两句什么意思     
           cyClient = HIWORD (lParam) ;       
            return 0 ;                      
       case   WM_PAINT:      
            hdc = BeginPaint (hwnd, &ps) ;                       
            MoveToEx (hdc, 0,cyClient / 2, NULL) ;    // 移到下一个点？为什么要除2
            LineTo   (hdc, cxClient, cyClient / 2) ;   // 为什么只有y除以2？                   
            for (i = 0 ; i < NUM ; i++)       
         {       
             apt[i].x = i * cxClient / NUM ;
             apt[i].y = (int) (cyClient / 2 * (1 - sin (TWOPI * i / NUM))) ;  // 循环确定点的坐标放到数组中？
      
         }                     
            Polyline (hdc, apt, NUM) ;       // 这个函数怎么实现的？
            return 0 ;                     
        case   WM_DESTROY:       
            PostQuitMessage (0) ;      
            return 0 ;       
    }       
    return DefWindowProc (hwnd, message, wParam, lParam) ;       
}