C# DateTime parse short string ("MMMyy")

Question

I have a string which contains date and has a format of "MMMyy". How would it be possible to do that?
Sample:

string date = "MAY09";
DateTime a = DateTime.Parse("MAY09"); //Gives "2012.05.09 00:00:00"
DateTime b = DateTime.ParseExact("MAY09", "MMMyy", null); //Gives error
DateTime c = Convert.ToDateTime("MAY09"); //Gives "2012.05.09 00:00:00"

I need "2009-05-01"

Answer 1

Specify invariant culture fore the third parameter instead of null:

DateTime b = DateTime.ParseExact("MAY09", "MMMyy", CultureInfo.InvariantCulture);

Answer 2

The second one is what you want - other than using the right culture. null says to use the date/time format information from the current culture - which will fail if it's not an English culture. (It's not clear from your user profile where you are, but presumably not in an English culture?)

Specifying the invariant culture is an easy way of getting English month/day names:

using System;
using System.Globalization;

class Test
{
    static void Main()
    {
        string text = "MAY09";
        string pattern = "MMMyy";
        var culture = CultureInfo.InvariantCulture;
        DateTime value = DateTime.ParseExact(text, pattern, culture);
        Console.WriteLine(value.ToString("yyyy-MM-dd", culture));
    }
}