C# DateTime.Now precision

by

Why would DateTime.Now be made less precise than what most CPU clocks could handle?

A good clock should be both precise and accurate; those are different. As the old joke goes, a stopped clock is exactly accurate twice a day, a clock a minute slow is never accurate at any time. But the clock a minute slow is always precise to the nearest minute, whereas a stopped clock has no useful precision at all.

Why should the DateTime be precise to, say a microsecond when it cannot possibly be accurate to the microsecond? Most people do not have any source for official time signals that are accurate to the microsecond. Therefore giving six digits after the decimal place of precision, the last five of which are garbage would be lying.

Remember, the purpose of DateTime is to represent a date and time. High-precision timings is not at all the purpose of DateTime; as you note, that’s the purpose of StopWatch. The purpose of DateTime is to represent a date and time for purposes like displaying the current time to the user, computing the number of days until next Tuesday, and so on.

In short, “what time is it?” and “how long did that take?” are completely different questions; don’t use a tool designed to answer one question to answer the other.

Thanks for the question; this will make a good blog article! 🙂

More Related Contents:

  1. How do I calculate someone’s age based on a DateTime type birthday?
  2. Parse string to DateTime in C#
  3. Convert UTC/GMT time to local time
  4. Creating a DateTime in a specific Time Zone in c#
  5. Is floating-point math consistent in C#? Can it be?
  6. How to truncate milliseconds off of a .NET DateTime
  7. format date in c#
  8. calculating the difference in months between two dates
  9. How to get client date and time in ASP.NET?
  10. What does “DateTime?” mean in C#?
  11. Format a date in XML via XSLT
  12. How to compare DateTime in C#?
  13. Environment.TickCount vs DateTime.Now
  14. Why DateTime.AddHours doesn’t seem to work?
  15. Convert DateTime for MySQL using C#
  16. How to convert Javascript datetime to C# datetime?
  17. How to find the 3rd Friday in a month with C#?
  18. How does DateTime.ToUniversalTime() work?
  19. Convert DateTime to Julian Date in C# (ToOADate Safe?)
  20. Difference between System.DateTime.Now and System.DateTime.Today
  21. why does DateTime.ToString(“dd/MM/yyyy”) give me dd-MM-yyyy?
  22. How to ensure a timestamp is always unique?
  23. datetime to string with time zone
  24. How frequent is DateTime.Now updated ? or is there a more precise API to get the current time?
  25. Days, hours, minutes, seconds between two dates
  26. Convert DateTime to long and also the other way around
  27. Convert Date from Persian to Gregorian
  28. Unix time conversions in C# [duplicate]
  29. .NET: Why is TryParseExact failing on Hmm and Hmmss?
  30. LINQ Query to Convert string to datetime

Leave a Comment