Unable to Parse DateTime in asp.net from excel file of the format - 25-OCT-13 01.08.24.732000000 PM

Question

The excel file I am reading has the datetime column value as "25-OCT-13 01.08.24.732000000 PM" and to read it into .Net's DateTime format I tried

DateTime.TryParseExact(certDate, "dd-MMM-yy hh.mm.ss.fffffffff tt", CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None, out certifiedDateTime) 

but it always is false. What am i missing.

I am using C# in Visual Studio 2013, .Net 4.5

Answer 1

Appears you can only have up to 7 f elements.

This works:

string certDate = "25-Oct-13 01.08.24.7320000 PM";
DateTime certifiedDateTime;
DateTime.TryParseExact(certDate, "dd-MMM-yy hh.mm.ss.fffffff tt", 
   CultureInfo.InvariantCulture, 
   System.Globalization.DateTimeStyles.None, 
   out certifiedDateTime);
certifiedDateTime.Dump();

It seems this is because DateTime is stored as a 64-bit number representing ticks. There's a good relevant article from Eric Lippert called Precision and accuracy of DateTime.

To get that additional precision you may have to look at a different library. Perhaps Jon Skeet's Noda Time, though that may not help either.

However, I'm guessing you don't actually want sub-second precision to 9 decimal places (particularly as it's unlikely you have that in the raw data unless the trailing zeroes are a big coincidence).

As such, if you're happy sacrificing this excess precision you could use Regex or similar to parse out the milliseconds and reduce them to 7 digits.

As such, if you're happy sacrificing the excess precision, MarcinJuraszek's comment to use a format including 0 sounds like the best approach:

DateTime.TryParseExact(certDate, "dd-MMM-yy hh.mm.ss.fffffff00 tt", 
   CultureInfo.InvariantCulture, 
   System.Globalization.DateTimeStyles.None, 
   out certifiedDateTime);