Question

I have 2 collections of objects. the objects have an object-type ‘key’ property (I use object.ReferenceEquals to test the key). how do I merge collection A and B to produce a distinct collection C that has all the items of A and B but not those of A that have a matching key with an item in B?

EDIT: mind you, the collections might also be empty.

Answer 1

This should work:

var toMergeA = A.Where(x => !B.ContainsKey(x.Key));
var C = toMergeA.Union(B);