C / C++ / MFC

 void CMainFrame::OnExportPdf()
{
    // TODO: Add your command handler code here
    CExportPro*  ExPro;
    ExPro = new CExportPro();
    CFileDialog  dlg(FALSE,TEXT("txt"),NULL,OFN_HIDEREADONLY|OFN_FILEMUSTEXIST|OFN_PATHMUSTEXIST|OFN_OVERWRITEPROMPT,_T("TXT (*.txt) |*.txt|")); 
    CString   fileName;
    CString   filePath;
   if(dlg.DoModal()==IDOK )
   {
       ExPro->SetCaption(TEXT("pdf"));
       ExPro->Create();
       ExPro->ShowWindow(SW_SHOW);
       filePath = dlg.GetPathName();
       m_filepathname = dlg.GetPathName();
     //  AfxBeginThread(WriteFile,this);
       if ( !filePath.IsEmpty())
       {
           CFile file;
           CString str(TEXT("hello this is the test for write process"));
           file.Open(filePath.GetBuffer(),CFile::modeCreate|CFile::modeWrite);
           while (i<1000000)
           {
               file.Write(str,str.GetLength());
               i++;
           }
           file.Close();
       }
   }
}

BOOL CExportPro::OnInitDialog()
{
    CDialogEx::OnInitDialog();
    SetWindowText(m_StrCaption);
    m_avi.Open(IDR_AVI1);
    m_avi.Play(0,-1, -1);
    return TRUE;
}