Question

Lets say I have a Dictionary object:

Dictionary myDictionary<int, SomeObject> = new Dictionary<string, SomeObject>(); 

Now I want to iterate through the dictionary in reverse order. I can’t use a simple for loop because I don’t know the keys of the dictionary. A foreach is easy:

foreach (SomeObject object in myDictionary.Values) {     // Do stuff to object } 

But how can I perform this in reverse?

Answer 1

I’d use a SortedList instead of a dictionary. You can still access it by Key, but you can access it by index as well.

SortedList sCol = new SortedList();  sCol.Add('bee', 'Some extended string matching bee'); sCol.Add('ay', 'value matching ay'); sCol.Add('cee', 'Just a standard cee');  // Go through it backwards. for (int i = sCol.Count - 1; i >=0 ; i--)     Console.WriteLine('sCol[' + i.ToString() + '] = ' + sCol.GetByIndex(i));  // Reference By Key foreach (string i in sCol.Keys)     Console.WriteLine('sCol[' + i + '] = ' + sCol[i]);  // Enumerate all values foreach (string i in sCol.Values)     Console.WriteLine(i); 

It’s worth noting that a sorted list stores key/value pairs sorted by key only.