c# - How can I convert a date string from format X to format Y?

Question

I have a string containing a date in some format X (e.g. 12/31/2015). How can I convert it to format Y (e.g. 2015-12-31 00:00:00)?

Answer 1

C# has it's own DateTime structure. The goal is to

1. convert your string to a DateTime and then
2. convert your DateTime back to a string.

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First, you need to get the format string for both formats X and Y. Check the following two lists:

• Standard Date and Time Format Strings
• Custom Date and Time Format Strings

E.g., for 12/31/2015, all of d or MM/dd/yyyy (with the en-US or invariant culture) or MM/dd/yyyy (with any locale) would be fine. For 2015-12-31 00:00:00, it would be yyyy-MM-dd HH:mm:ss.

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For the first step, you can use DateTime.ParseExact (or DateTime.TryParseExact, if you want to fail gracefully if the string does not have the correct format), e.g.,

var myDateTime = DateTime.ParseExact(myInputString, "MM/dd/yyyy",
                                     CultureInfo.InvariantCulture);

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For the second step, use DateTime.ToString:

var myOutputString = myDateTime.ToString("yyyy-MM-dd HH:mm:ss",
                                         CultureInfo.InvariantCulture);