Monday, June 05, 2006

Converting dd/MM/yyyy strings to Datetimes in .NET

It's not easy to find documentation on "How to parse a string into a DateTime variable in .NET?". I had to create an application that parsed a date entered as dd/MM/yyyy, and I had to ensure the code would run on any system, including U.S. based computers which would have the culture info set to MM/dd/yyyy.

All documentation points to the DateTime.Parse() method. Now this method is of no real use, because it always uses the culture information, which according to me is a no-entry zone because heck, all I want to do is parse a date, not change a whole culture.

Now there's this other function named DateTime.ParseExact( string s, string Format, IFormatProvider provider). This is EXACTLY what I needed, except I didn't know what to do with the provider parameter. All the documentation says is "An IFormatProvider that supplies culture-specific format information about s."

Another mention of the dreaded "culture". I tried to understand what this IFormatProvider was, and got to some custom class that converts strings to radixes (whatever they are). I don't know any culture that has radixes but I might have been living in a shell somewhere and all of this just happened.

Completely flummoxed, I thought, "to heck with this culture and IFormatProvider business" and passed "null" instead, and I got exactly what I wanted.

All you have to do is call:

DateTime d = DateTime.ParseExact( s, "dd/MM/yyyy", null);

and the string s will get converted to a DateTime, if it's in the dd/MM/yyyy format.

I wish they'd mentioned "optional" in the documentation for the provider parameter.

10 Comments:

Blogger dontEATnachos said...

Hey, thanks for posting this. I was trying to solve the same IFormatProvider (and had seen that with MC++ it was optional) but did not think of just throwing a null int there.

3:36 PM  
Blogger Deepak Shenoy said...

Glad to help. I found that problem a pain in the neck too.

9:54 PM  
Blogger Kannan M Ambadi said...

thanks man.....great work !!

7:45 AM  
Blogger mhalottering said...

Perhaps worth mentioning though is that when the user enters 1/1/2008 instead of 01/01/2008, this method also falls over.

I catch an exception on the first attempt, and retry using "d/M/yyyy", which works.

12:34 AM  
Blogger koi said...

Great work man thanks,I have searched many..:)))

Vivek

4:48 AM  
Blogger Srgrn said...

Thanks i was about to stop using dd/MM/yyyy

12:30 AM  
Blogger untypical sort of said...

Thank you, SIR!! That's a nice way to solve a vexing problem!

6:30 PM  
Blogger Prateek said...

Thanks a million!
Your post was of gr8 use!

7:10 AM  
Blogger Bala Sakthis said...

Hi Shenoy,
Thanks! for providing a wonderful solution. I googled for solution and those didn't provide the expected result. But yours worked like a charm. Thanks! a lot.


-- Bala

10:24 AM  
Blogger Nik said...

rather than using a try/catch construct for different variations of expected date formats, use the overloaded method that accepts a list of accepted formats:

string[] validDateFormats = { @"M/d/yyyy", @"MM/dd/yyyy" };

myDate = = DateTime.ParseExact(processDateTextBox.Text, validDateFormats, null, System.Globalization.DateTimeStyles.None);

- and knowing is half the battle

3:40 PM  

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