Parse through date of a filename

Question

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So I need to parse through a date of a filename. So far example I have a file and the date is

Accounts_2012017

The problem I have at the moment is the format of the date is something like "M/dd/yyyy" and so every time I use ParseExact,
I get an error that the string is not a valid DateTime, even if I do "MM/dd/yyyy". What are my other options to pick this date out?

The above date reads as: February 1st 2017

What I have tried:

C#

string temp = filename.Replace(".txt", "").Substring(filename.LastIndexOf('_') + 1);
           DateTime extracted = DateTime.ParseExact(temp, "Mddyyyy", System.Globalization.CultureInfo.InvariantCulture);

Posted 2-Feb-17 6:35am

SmartDeveloping

Updated 2-Feb-17 17:18pm

v3

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Comments

Dave Kreskowiak 2-Feb-17 12:49pm

A quick solution would be to get the date string, check it's length, then switch to an appropriate parse string, one for one digit months and one for two digit months.

Really, your data is what's the problem. In a normalized format, you would have a consistent number of digits for all month , day, and year numbers. This means leading zeros on values to fill the required number of digits to maintain consistency in the data.

SmartDeveloping 2-Feb-17 12:50pm

Dave, unfortunately that is the sad part that it isn't in a normalized format or I wouldn't even have this problem.

[no name] 2-Feb-17 13:20pm

Use an If statement to check the length of temp and add a "0" to the front of the string if the length is not 8. If whomever is giving you these filename is not going to noramlize them for you, you are going to have to do it yourself.

[no name] 2-Feb-17 13:31pm

You didn't read the comment very well did you?

SmartDeveloping 2-Feb-17 13:41pm

Sorry, I understand what you mean.

2 solutions

Solution 1

According to the example filename you posted, your format string is incorrect. It should be "yyyyMdd". BTW, if it's not too late to change it, it would be better if you used a two-digit month. That way, there's no confusion about what the date is, and your parsing will always work.

I don't personally think you'll be able to reliable parse the date because you're allowing the month to be represented by a single digit. To mitigate that aspect of the filename, you could check the length of the string that represents the date, and if it's less than 8, prepend it with a zero. At that point, you could change your format string to "MMddyyyy", and it will parse correctly every time (assuming, of course that the day is always represented by two digits).

FWIW, you should also consider breaking that statement up into discrete parts so you can correct the date (and handle errors) more easily.

Posted 2-Feb-17 6:43am

#realJSOP

Updated 2-Feb-17 7:16am

v4

Comments

SmartDeveloping 2-Feb-17 12:45pm

Error:String was not recognized as a valid DateTime. Not sure how the "yyyyMdd" would help because 2017 is at the end of it. The date reads February 1st 2017.

#realJSOP 2-Feb-17 13:14pm

Updated my answer.

SmartDeveloping 2-Feb-17 13:17pm

Unfortunately I cannot change the code of how the file is padded, because I am getting it from third party. I am checking the length, lets see if I can prepend it.

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Karthik_Mahalingam · Accepted Answer · 2017-02-02T17:18:00

Solution 2

try this
it will work for "MMddyyyy" and "Mddyyyy"

string filename = "Accounts_2012017.txt";
           string temp = filename.Replace(".txt", "").Substring(filename.LastIndexOf('_') + 1);
           string format = (temp.Length == 7) ? "Mddyyyy" : "MMddyyyy";
           DateTime extracted = DateTime.ParseExact(temp, format, System.Globalization.CultureInfo.InvariantCulture);

Posted 2-Feb-17 17:18pm

Karthik_Mahalingam

Comments

SmartDeveloping 3-Feb-17 15:19pm

Thanks a lot, I was able to make it work with something similar.

Karthik_Mahalingam 3-Feb-17 15:20pm

good,