最简单的创建一个窗口,为什么会失败?

Question

HWND m_hWndSocket = NULL; WNDCLASS wndCls;
wndCls.style = CS_HREDRAW | CS_VREDRAW;
wndCls.cbClsExtra = 0;
wndCls.cbWndExtra = 0;
wndCls.hbrBackground = 0;
wndCls.hCursor = NULL;
wndCls.hIcon = NULL;
wndCls.hInstance = NULL;
wndCls.lpfnWndProc = SocketWndProc;
wndCls.lpszMenuName = NULL;
wndCls.lpszClassName = "FPSSocketWnd"; cout<<"reg:"<<RegisterClass(&wndCls)<<endl; m_hWndSocket = ::CreateWindow("FPSSocketWnd","Socket",WS_POPUP,0,0,100,100, NULL,NULL,NULL,NULL); cout<<"m_hWndSocket:"<<m_hWndSocket<<endl;
if(m_hWndSocket == NULL)
{
cout<<GetLastError()<<endl;
}     注册窗口类成功了,为什么CreateWindow会失败呢?请教.

Answer 1

//窗口函数如下:
LRESULT CALLBACK SocketWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
return 0;
}

Answer 2

/********************************************************************
 *SDK窗口的创建步骤:
 *-Ctrl+N
 *-点击Projects 选项卡
 *-点击Win32 Application
 *-Project name:输入工程名称,然后OK
 *-选择An empty project.
 *-点击Finish完成,再点击OK *-然后点击上面的菜单Project
 *-点击Add To Project->New...
 *-点击Files选项卡
 *-选择C++ Source File
 *-File:输入文件名称
 *-点击OK
 *-最后把代贴进去,进行编译就OK了!
 **********************************************************************/
#include "windows.h"//窗口过程函数申明
LRESULT WINAPI WndProc(HWND,UINT,WPARAM,LPARAM);//Win32程序主函数WinMain
int WINAPI WinMain (HINSTANCE hInstance,
                    HINSTANCE hPrevInstance,
                    LPSTR lpCmdLine,
                    int nCmdShow)
{
    HWND hWnd;      // 主窗口句柄
    MSG msg;        // 窗口消息
    WNDCLASS wc;    // 窗口類

if (!hPrevInstance)
{ 
// 填充窗口類信息
wc.style = CS_HREDRAW|CS_VREDRAW;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(NULL,IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL,IDC_ARROW);
wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wc.lpszMenuName  = NULL;
wc.lpszClassName = "SdkDemo1";
// 註冊窗口類
RegisterClass(&wc);
} // 創建應用程序主窗口
hWnd=CreateWindow ("SdkDemo1",              // 窗口類名
"第一個Win32 SDK應用程序",         // 窗口標題
WS_OVERLAPPEDWINDOW,               // 窗口樣式
CW_USEDEFAULT,                     // 初始化 x 坐標
CW_USEDEFAULT,                     // 初始化 y 坐標
CW_USEDEFAULT,                     // 初始化窗口寬度
CW_USEDEFAULT,                     // 初始化窗口高度
NULL,                              // 父窗口句柄
NULL,                              // 窗口菜單句柄
hInstance,                         // 程序實例句柄
NULL);                             // 創建參數

    // 顯示窗口
    ShowWindow(hWnd,SW_SHOW);
    // 更新主窗口客戶區
    UpdateWindow(hWnd);
    // 開始消息循環
    while (GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}

return msg.wParam;

}// WndProc 主窗口過程
LRESULT WINAPI WndProc (HWND hWnd,
                        UINT msg,
                        WPARAM wParam,
                        LPARAM lParam)
{
//在窗口內畫一個圓形
HDC hdc;
RECT rc;
HPEN hPen,hPenOld;
HBRUSH hBrush,hBrushOld;
switch (msg)
{
    case WM_PAINT:
hdc=GetDC(hWnd);
GetClientRect(hWnd,&rc);
hPen=CreatePen(PS_SOLID,0,RGB(0,0,0));
hBrush=CreateHatchBrush(HS_DIAGCROSS,RGB(0,0,0));
hPenOld=(HPEN)SelectObject(hdc,hPen);
hBrushOld=(HBRUSH)SelectObject(hdc,hBrush);
Ellipse(hdc,rc.left,rc.top,rc.right,rc.bottom);
SelectObject(hdc,hPenOld);
SelectObject(hdc,hBrushOld);
ReleaseDC(hWnd,hdc);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:break;
}
return DefWindowProc(hWnd,msg,wParam,lParam);
}

Answer 3

摘自windows程序设计/*------------------------------------------------------------
   HELLOWIN.C -- Displays "Hello, Windows 98!" in client area
                 (c) Charles Petzold, 1998
  ------------------------------------------------------------*/#include <windows.h>LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("HelloWin") ;
     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,                  // window class name
                          TEXT ("The Hello Program"), // window caption
                          WS_OVERLAPPEDWINDOW,        // window style
                          CW_USEDEFAULT,              // initial x position
                          CW_USEDEFAULT,              // initial y position
                          CW_USEDEFAULT,              // initial x size
                          CW_USEDEFAULT,              // initial y size
                          NULL,                       // parent window handle
                          NULL,                       // window menu handle
                          hInstance,                  // program instance handle
                          NULL) ;                     // creation parameters
     
     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 ;
     PAINTSTRUCT ps ;
     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 98!"), -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) ;
}