windows新建一个窗口程序示例

程序步骤：

1，winmain函数定义

2，创建一个窗口

3，进行消息循环

4，编写窗口过程函数。

看代码，如下：

#include <windows.h>
#include <stdio.h>

LRESULT CALLBACK WinSunProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
);

int WINAPI WinMain(
  HINSTANCE hInstance,      // handle to current instance
  HINSTANCE hPrevInstance,  // handle to previous instance
  LPSTR lpCmdLine,          // command line
  int nCmdShow              // show state
)
{
    WNDCLASS wndcls;
    wndcls.cbClsExtra=0;
    wndcls.cbWndExtra=0;
    wndcls.hbrBackground=(HBRUSH)GetStockObject(BLACK_BRUSH);
    wndcls.hCursor=LoadCursor(NULL,IDC_ARROW);
    wndcls.hIcon=LoadIcon(NULL,IDI_ERROR);
    wndcls.hInstance=hInstance;
    wndcls.lpfnWndProc=WinSunProc;
    wndcls.lpszClassName="Weixin2003";
    wndcls.lpszMenuName=NULL;
    wndcls.style=CS_HREDRAW | CS_VREDRAW;
    RegisterClass(&wndcls);

    HWND hwnd;
    hwnd=CreateWindow("Weixin2003","北京维新科学技术培训中心",WS_OVERLAPPEDWINDOW&~WS_MINIMIZEBOX,
        300,100,500,400,NULL,NULL,hInstance,NULL);

    ShowWindow(hwnd,SW_SHOWNORMAL);
    UpdateWindow(hwnd);

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

LRESULT CALLBACK WinSunProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
)
{
    switch(uMsg)
    {
    case WM_CHAR:
        char szChar[20];
        sprintf(szChar,"char is %d",wParam);
        MessageBox(hwnd,szChar,"weixin",MB_OK );
        break;
    case WM_LBUTTONDOWN:  //鼠标左键按下的消息
        MessageBox(hwnd,"mouse clicked","weixin",0);
        HDC hdc;       //a handle to device context ，dc
        hdc=GetDC(hwnd);
        TextOut(hdc,20,50,"计算机编程语言培训",strlen("计算机编程语言培训"));
        ReleaseDC(hwnd,hdc);
        break;
       case WM_PAINT :  //窗口重绘时发生消息.
        HDC hDC;
        PAINTSTRUCT ps;//系统自己维护
        hDC=BeginPaint(hwnd,&ps);
        TextOut(hDC,0,0,"维新培训",strlen("维新培训"));
        EndPaint(hwnd,&ps);
        break;

    case WM_CLOSE:  //Sent as a signal that a window or an application should terminate.
    
        {
            DestroyWindow(hwnd); //destroy teh specified windows
        }    /*Destroys the specified window. The function sends WM_DESTROY
        and WM_NCDESTROY messages to the window to deactivate it and
        remove the keyboard focus from it.只是销毁窗口，并没有退出程序 */
        break;
    case WM_DESTROY:  //
        if(IDYES==MessageBox(hwnd,"是否真的结束？","weixin",MB_YESNO))
        PostQuitMessage(0); 
        break;
    default:
        return DefWindowProc(hwnd,uMsg,wParam,lParam);//对不感兴趣缺省处理 不能少这行，否则不显示.
    }
    return 0;
}

 注意WinMain相当于main函数，跟c一样，在main后面定义的函数有先声明，否则出错。

运行结果如图；

注意：若写成

HWND hwnd;
hwnd=CreateWindow("Weixin2003","北京维新科学技术培训中心",WS_OVERLAPPEDWINDOW&~WS_MINIMIZEBOX,
300,100,500,400,NULL,NULL,hInstance,NULL);

MSG msg;

while(GetMessage(&msg,hwnd,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}

你只想获取hwnd窗口的句柄，关闭程序，发现程序还在后台运行，没有退出，为什么？

GetMessage当hwnd为无效的窗口句柄或lpMsg参数为无效的指针，返回-1，程序并没有退出。

  当你退出时，窗口被销毁，hwnd为无效句柄，所以一直是-1，陷入了死循环，机器变慢了。

msdn建议：

The possibility of a -1 return value means that such code can lead to fatal application errors. Instead, use code like this:

BOOL bRet;

while( (bRet = GetMessage( &msg, hWnd, 0, 0 )) != 0)
{ 
    if (bRet == -1)
    {
        // handle the error and possibly exit 

       写成return -1；
    }
    else
    {
        TranslateMessage(&msg); 
        DispatchMessage(&msg); 
    }
}