How to get the unix timestamp in C#

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

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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.Now.ToUnixTimeSeconds()

To get the timestamp from a DateTime:

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

You get a unix timestamp in C# by using DateTime.UtcNow and subtracting the epoch time of 1970-01-01.

e.g.

Int32 unixTimestamp = (Int32)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;

DateTime.UtcNow can be replaced with any DateTime object that you would like to get the unix timestamp for.

There is also a field, DateTime.UnixEpoch, which is very poorly documented by MSFT, but may be a substitute for new DateTime(1970, 1, 1)

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;