C# 如何生成一个时间戳

/// 获取时间戳
/// </summary>
/// <returns></returns>
public static string GetTimeStamp()
{
    TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
    return Convert.ToInt64(ts.TotalSeconds).ToString();
}