[C#] UnixTime (int)を取得する

public static int GetCurrentUnixTime()
{
   var unixTimestamp = (int)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;
   return unixTimestamp;
}

public static int GetUnixTime(DateTime timeStamp)
{
　　var unixTimestamp = (int)(timeStamp.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;
　　return unixTimestamp;
}

public static DateTime GetDateTimeFromUnixTime(int unixTimeStamp)
{
   DateTime dtDateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
   dtDateTime = dtDateTime.AddSeconds(unixTimeStamp).ToLocalTime();
            return dtDateTime;
}