Question

I have a system that outputs dates in the format “1{yy}{MM}{dd}” and I am trying to find a good way to parse it back into a real date.
At the moment I am using this:

  var value = "1110825";
  var z = Enumerable.Range(1,3).Select(i => int.Parse(value.Substring(i, 2))).ToList();
  var d = new DateTime(2000 + z[0], z[1], z[2]);

but I’m sure there’s a cleaner/more efficient way to do it?

I’ve tried DT.ParseExact, but can’t find a suitable format string to use.

Answer 1

This works for me:

using System;
using System.Globalization;

public class Test
{
    static void Main()
    {
        var value = "1110825";
        DateTime dt = DateTime.ParseExact(value, "1yyMMdd",
                                          CultureInfo.InvariantCulture);
        Console.WriteLine(dt);
    }
}

(You may want to use TryParseExact of course, if you need to cope with invalid data in any way other than with an exception.)

A slight variation of this is the format pattern of “‘1’yyMMdd” – note the apostrophes round the 1. That quotes the 1 to force it to be treated as a “literal” in the pattern. It’s not important in this case, but if you actually had values such as “y110825” then you’d want to quote the y to make sure it wasn’t treated as part of a year specifier.