Question

You would think that if two dictionaries contained the same keys and values they would return the same hash code and be equal right? but they don’t – what am i doing wrong? or how do I compare dictionaries in this way?

Thanks. Code sameple below

/In this case I also want to test the order is the same/equal.

     SortedDictionary<int,string> sd1 = new SortedDictionary<int,string>();
        sd1.Add(1,"one");
        sd1.Add(2, "two");
        sd1.Add(5, "five");
        int sd1Hash = sd1.GetHashCode();

        SortedDictionary<int, string> sd2 = new SortedDictionary<int, string>();
        sd2.Add(1, "one");
        sd2.Add(2, "two");
        sd2.Add(5, "five");
        int sd2Hash = sd2.GetHashCode();

        //This is false
        bool areEqual = sd1.Equals(sd2);

Answer 1

If you want to test that the collections are equal, including their ordering:

bool areEqual = sd1.SequenceEqual(sd2);

If you wanted to treat the collections as unordered sets:

bool areEqual =
    (sd1.Count == sd2.Count) && (sd1.Intersect(sd2).Count() == sd1.Count);

(SequenceEqual and Intersect can also take an IEqualityComparer parameter, if required.)

As several other answers have stated, SortedDictionary doesn’t override the default implementations of Equals or GetHashCode. The default implementation of Equals will use reference equality and return false because you’re comparing two separate objects.