Question

I’ve a dictionary object:

Dictionary<string, string[]> dictCompanies = new Dictionary<string, string[]>(); 

How do sort this object on its key?

I tried using OrderBy like below, but it does no seem to work

dictCompanies .OrderByDescending(c=> c.Key);  

I’m binding this dictionary object to a checkboxlist in aspx page.

I tried sorting this ListItemCollection using delegate…but still no luck…

Am i missing something here?

Thanks

Answer 1

You can’t sort an actual Dictionary<TKey,TValue> – the order items come out of it is basically determined by the internal implementation. You might want to look at SortedDictionary<TKey,TValue> and SortedList<TKey,TValue> though – they still have key/value lookups, but allow you to sort based on the key. You can specify your own IComparer<T> if you want to order by the keys in a particular way.

Another option (depending on your situation) would be to stick with the dictionary right up until you need it – then copy it into a list and sort that before binding to the control. Obviously at that point you’d need to refresh the binding every time anything changed, but that may well not be a problem for you.

If your OrderBy statement was really on its own like that, by the way, you need to understand that LINQ operators always operators always take a sequence and return a different sequence (or an aggregate result) – they never modify the sequence in-place. Indeed, they can’t as IEnumerable<T> is a read-only interface.