How to get the unix timestamp in C#

Question

I have had look around stackoverflow, and even looked at some of the suggested questions and none seem to answer, how do you get a unix timestamp in C#?

Answer 1

Truncating .TotalSeconds is important since it's defined as the value of the current System.TimeSpan structure expressed in whole fractional seconds.

And how about an extension for DateTime? The second one is probably more confusing that it's worth until property extensions exist.

/// <summary>
/// Converts a given DateTime into a Unix timestamp
/// </summary>
/// <param name="value">Any DateTime</param>
/// <returns>The given DateTime in Unix timestamp format</returns>
public static int ToUnixTimestamp(this DateTime value)
{
    return (int)Math.Truncate((value.ToUniversalTime().Subtract(new DateTime(1970, 1, 1))).TotalSeconds);
}

/// <summary>
/// Gets a Unix timestamp representing the current moment
/// </summary>
/// <param name="ignored">Parameter ignored</param>
/// <returns>Now expressed as a Unix timestamp</returns>
public static int UnixTimestamp(this DateTime ignored)
{
    return (int)Math.Truncate((DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds);
}

Answer 2

I've spliced together the most elegant approaches to this utility method:

public static class Ux {
    public static decimal ToUnixTimestampSecs(this DateTime date) => ToUnixTimestampTicks(date) / (decimal) TimeSpan.TicksPerSecond;
    public static long ToUnixTimestampTicks(this DateTime date) => date.ToUniversalTime().Ticks - UnixEpochTicks;
    private static readonly long UnixEpochTicks = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).Ticks;
}

Answer 3

This is what I use.

 public class TimeStamp
    {
        public Int32 UnixTimeStampUTC()
        {
            Int32 unixTimeStamp;
            DateTime currentTime = DateTime.Now;
            DateTime zuluTime = currentTime.ToUniversalTime();
            DateTime unixEpoch = new DateTime(1970, 1, 1);
            unixTimeStamp = (Int32)(zuluTime.Subtract(unixEpoch)).TotalSeconds;
            return unixTimeStamp;
        }
}

Answer 4

You can also use Ticks. I'm coding for Windows Mobile so don't have the full set of methods. TotalSeconds is not available to me.

long epochTicks = new DateTime(1970, 1, 1).Ticks;
long unixTime = ((DateTime.UtcNow.Ticks - epochTicks) / TimeSpan.TicksPerSecond);

or

TimeSpan epochTicks = new TimeSpan(new DateTime(1970, 1, 1).Ticks);
TimeSpan unixTicks = new TimeSpan(DateTime.UtcNow.Ticks) - epochTicks;
double unixTime = unixTicks.TotalSeconds;

Answer 5

As of .NET 4.6, there is DateTimeOffset.ToUnixTimeSeconds().

---

This is an instance method, so you are expected to call it on an instance of DateTimeOffset. You can also cast any instance of DateTime, though beware the timezone.

To get the current timestamp:

DateTimeOffset.UtcNow.ToUnixTimeSeconds()

To get the timestamp from a DateTime:

DateTime foo = DateTime.UtcNow;
long unixTime = ((DateTimeOffset)foo).ToUnixTimeSeconds();

Answer 6

When you subtract 1970 from the current time, be aware that the timespan will most often have a non zero milliseconds field. If for some reason you are interested in the milliseconds, keep this in mind.

Here's what I did to get around this issue.

 DateTime now = UtcNow();

 // milliseconds Not included.
 DateTime nowToTheSecond = new DateTime(now.Year,now.Month,now.Day,now.Hour,now.Minute,now.Second); 

 TimeSpan span = (date - new DateTime(1970, 1, 1, 0, 0, 0, 0));

 Assert.That(span.Milliseconds, Is.EqualTo(0)); // passes.