C# 將byte[] 轉換為 string

MemoryStream stream = new MemoryStream();
        byte[] buffer = null;
        String gride = null;
ASPxPivotGridExporter1.ExportToHtml(stream, "utf-8", "ASPxPivotGrid Printing Sample", true);
            buffer=stream.GetBuffer();
            gride = (new UTF8Encoding()).GetString(buffer, 0, buffer.Length);最關鍵的是最後一句