Question

I am creating a custom type DateOnly which is effectively a DateTime with the Time portion removed.

I have run into a small problem where I want to format the Value of my new type like a date:

Dim startDate As New DateOnly(2012, 1, 2)
Debug.WriteLine(String.Format("{0:ddd}", startDate))

This outputs: 02/01/2012, I want to be able to format this to be Mon

Note: I haven’t included any of my code for the DateOnly type (to keep things simple) but I can add it if requested

Answer 1

I have managed to answer my own problem by implementing IFormattable in my custom type:

Public Overloads Function ToString(fmt As String, provider As IFormatProvider) As String Implements IFormattable.ToString
    Return String.Format("{0:" + fmt + "}", _dateValue)
End Function

This seems to do the trick.