函数原型:
CFileDialog(BOOL bOpenFileDialog,LPCTSTR lpszDefExt=NULL,LPCTSTR lpszFileName=NULL,DWORD dwFlags = OFN_HIDEREADONLY | OFN_OVERWRITEPR OMPT,LPCTSTR lpszFilter=NULL,CWnd * pParentWnd=NULL); CFileDialog(BOOL bOpenFileDialog,LPCTST