C# / .NET - subtract nanoseconds from DateTime

In C# / .NET it is possible to subtract nanoseconds from DateTime object in following way.

1. DateTime.AddTicks method example

long nanoseconds = 500;

DateTime time1 = new DateTime(2012, 1, 1, 12, 0, 0, 100);
DateTime time2 = time1.AddTicks(-nanoseconds / 100);

Console.WriteLine($"Old time: {time1:o}");
Console.WriteLine($"New time: {time2:o}");

Output:

Old time: 2012-01-01T12:00:00.1000000
New time: 2012-01-01T12:00:00.0999995

Note: maximum precision for DateTime structure is 100 ns, so it is impossible to see difference during operating on times that are smaller than 100 ns.

2. DateTime.Subtract method example

long nanoseconds = 500;

DateTime time1 = new DateTime(2012, 1, 1, 12, 0, 0, 100);
DateTime time2 = time1.Subtract(TimeSpan.FromTicks(nanoseconds / 100));

Console.WriteLine($"Old time: {time1:o}");
Console.WriteLine($"New time: {time2:o}");

Output:

Old time: 2012-01-01T12:00:00.1000000
New time: 2012-01-01T12:00:00.0999995

Note: maximum precision for DateTime structure is 100 ns, so it is impossible to see difference during operating on times that are smaller than 100 ns.

References

1. DateTime.AddTicks Method - Microsoft docs
2. DateTime.Subtract Method - Microsoft docs