{
    Response.Clear();
    Response.Buffer = true;
    Response.AddHeader("content-disposition", "attachment;filename=Report.csv");
    Response.Charset = "";
    Response.ContentType = "application/text";
    gvReport.AllowPaging = false;
    StringBuilder sBuilder = new System.Text.StringBuilder();
    for(int index = 0; index < gvReport.Columns.Count; index++)
    {
        sBuilder.Append(gvReport.Columns[index].HeaderText + ',');
    }
    sBuilder.Append("rn");
    for(int i = 0; i <gvReport.Rows.Count; i++)
    {
        for(int k = 0; k < gvReport.HeaderRow.Cells.Count; k++)
        {
            sBuilder.Append(gvReport.Rows[i].Cells[k].Text.Replace(",","") + ",");
        }
        sBuilder.Append("rn");
    }
    Response.Output.Write(sBuilder.ToString());
    Response.Flush();
    Response.End();
}

var sBuilder = new StringBuilder();
    foreach (DataGridViewRow row in gridSchedules.Rows)
    {
        // RowHeader
        sBuilder.Append(String.Concat(row.HeaderCell.Value, ";"));

        // Cells
        foreach (DataGridViewCell cell in row.Cells)
        {
            sBuilder.Append(String.Concat(cell.Value, ";"));
        }
        sBuilder.Append(Environment.NewLine);
    }