C# - Convert DateTime to Long and Vice Versa

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1long.Parse(DateTime.UtcNow.ToString("yyyyMMddHHmmss"))

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1private static DateTime? GetDateTimeFromInt(long? dateAsLong, bool hasTime = true)
2{
3    if (dateAsLong.HasValue && dateAsLong > 0)
4    {
5        if (hasTime)
6        {
7            // sometimes input is 14 digit and sometimes 16
8            var numberOfDigits = (int)Math.Floor(Math.Log10(dateAsLong.Value) + 1);
9
10            if (numberOfDigits > 14)
11            {
12                dateAsLong /= (int)Math.Pow(10, (numberOfDigits - 14));
13            }
14        }
15
16        if (DateTime.TryParseExact(dateAsLong.ToString(), hasTime ? "yyyyMMddHHmmss" : "yyyyMMdd",
17                                  CultureInfo.InvariantCulture,
18                                  DateTimeStyles.None, out DateTime dt))
19        {
20            return dt;
21        }
22    }
23
24    return null;
25}