一个简单的win32窗口

#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_CROSS);
 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,
  0,0,600,400,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",0);
  break;
 case WM_LBUTTONDOWN:
  MessageBox(hwnd,"mouse clicked","weixin",0);
  HDC hdc;
  hdc=GetDC(hwnd);
  TextOut(hdc,0,50,"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:
  HDC hDC;
  PAINTSTRUCT ps;
  hDC=BeginPaint(hwnd,&ps);
  TextOut(hDC,0,0,"维新培训",strlen("维新培训"));
  EndPaint(hwnd,&ps);
  break;
 case WM_CLOSE:
  if(IDYES==MessageBox(hwnd,"是否真的结束？","weixin",MB_YESNO))
  {
   DestroyWindow(hwnd);
  }
  break;
 case WM_DESTROY:
  PostQuitMessage(0);
  break;
 default:
  return DefWindowProc(hwnd,uMsg,wParam,lParam);
 }
 return 0;
}