如何使用C＃/ .NET将日期时间转换为时间戳（忽略当前时区）

Question

How do I convert datetime to timestamp using C# .NET (ignoring the current timezone)?

I am using the below code:

private long ConvertToTimestamp(DateTime value)
{
    long epoch = (value.ToUniversalTime().Ticks - 621355968000000000) / 10000000;
    return epoch;
}

But it returns the timestamp value according to the current time zone & and I need the result without using the current timezone.

Answer 1

At the moment you're calling ToUniversalTime() - just get rid of that:

private long ConvertToTimestamp(DateTime value)
{
    long epoch = (value.Ticks - 621355968000000000) / 10000000;
    return epoch;
}

Alternatively, and rather more readably IMO:

private static readonly DateTime Epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
...

private static long ConvertToTimestamp(DateTime value)
{
    TimeSpan elapsedTime = value - Epoch;
    return (long) elapsedTime.TotalSeconds;
}

EDIT: As noted in the comments, the Kind of the DateTime you pass in isn't taken into account when you perform subtraction. You should really pass in a value with a Kind of Utc for this to work. Unfortunately, DateTime is a bit broken in this respect - see my blog post (a rant about DateTime ) for more details.

You might want to use my Noda Time date/time API instead which makes everything rather clearer, IMO.

Answer 2

I'm not exactly sure what it is that you want. Do you want a TimeStamp? Then you can do something simple like:

TimeStamp ts = TimeStamp.FromTicks(value.ToUniversalTime().Ticks);

Since you named a variable epoch, do you want the Unix time equivalent of your date?

DateTime unixStart = DateTime.SpecifyKind(new DateTime(1970, 1, 1), DateTimeKind.Utc);
long epoch = (long)Math.Floor((value.ToUniversalTime() - unixStart).TotalSeconds);

Answer 3

Find timestamp from DateTime:

private long ConvertToTimestamp(DateTime value)
{
    TimeZoneInfo NYTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
    DateTime NyTime = TimeZoneInfo.ConvertTime(value, NYTimeZone);
    TimeZone localZone = TimeZone.CurrentTimeZone;
    System.Globalization.DaylightTime dst = localZone.GetDaylightChanges(NyTime.Year);
    NyTime = NyTime.AddHours(-1);
    DateTime epoch = new DateTime(1970, 1, 1, 0, 0, 0, 0).ToLocalTime();
    TimeSpan span = (NyTime - epoch);
    return (long)Convert.ToDouble(span.TotalSeconds);
}

Answer 4

JonSkeet有一个很好的答案，但作为一种替代方案，如果你想保持结果更便携，你可以将日期转换为ISO 8601格式，然后可以将其读入大多数其他框架，但这可能超出您的要求。

value.ToUniversalTime().ToString("O");