SortedList/SortedDictionary weird behavior

Question

Can anybody explain why this code:

Dim Data As New SortedList(StringComparer.InvariantCultureIgnoreCase)
Data.Add("AB", 48)
Data.Add("AC", 48)
Data.Add("A-D", 48)
Data.Add("A-", 48)

Generates sorted list with following order:

A-  
AB  
AC  
A-D

Expected (logical and really wanted) order is:

A-
A-D
AB
AC

Answer 1

Dim Data As New SortedList(StringComparer.InvariantCultureIgnoreCase)

I think the problem is with the sort rules specified.

Changing InvariantCultureIgnoreCase to Ordinal or OrdinalIgnoreCase solves the problem

Dim Data As New SortedList(StringComparer.OrdinalIgnoreCase)

Here is the Demo

Answer 2

That is how default string comparer is implemented. To customize this you have to implement your own custom IComparer or for better compatibility override Comparer<T> class and pass it to SortedList constructor or pass StringComparer.OrdinalIgnoreCase.