private void btnExit_Click(object sender, EventArgs e) { SaveFileDialog sf = new SaveFileDialog(); sf.Filter = "Excel Filles(*,xls)|*.xls"; sf.CheckFileExists = false; sf.CheckPathExists = false; sf.FilterIndex = 0; sf.RestoreDirectory = true; sf.CreatePrompt = true; if (sf.ShowDialog() == DialogResult.OK) { Stream savestr = sf.OpenFile(); DataGridViewHelper.DataGridViewToExcel(dgvBook, savestr); } }