I was trying to use SortedDictionary to store some of my data from file, but got really weird bunch of key duplication exceptions. I came up with the next code sample which reproduces my issue:
var dict = new SortedDictionary<string, string>();
dict.Add("Æ", "qwerty"); // "aesc" (aka "ash"), single symbol
Console.WriteLine(dict["AE"]); // outputs "qwerty" for two-symbol string "AE"
dict.Add("AE", ""); // ArgumentException: An entry with the same key already exists.
It's not happening for usual Dictionary though and I finally decided to use it instead. But I still wonder why is it a problem for a sorted one? Unfortunatelly, I was unable to google an answer myself (got a lot of AES-related noise) and can't debug into SortedDictionary's code despite MS recently made some of .NET source code open.
It's almost seems like this class implicitly runs some string preprocessing/normalization function, but I just can't believe it is an actual reason.
Any ideas why is it happening? Thanks in advance!
It's because of the culture. Try new SortedDictionary(StringComparer.Ordinal), for example.
The reason Dictionary behaves differently is that it uses EqualityComparer<TKey>.Default while SortedDictionary uses Comparer<TKey>.Default.