Question

I have two sortedlists

 1. oldlist<int,int> 

 2. newlist <int,int>

(application specific information – key is industryId and value is weight)

I want to compare the changes in the lists.

I want the following things –

• list of items where weight was not zero, but its zero in the newlist.

• list of items where weight is not zero and has changed from oldlist.

I know there is something called as comparer.
can it be used here ?

Answer 1

You can use Linq:

// list of items where weight was not zero, but its zero in the newlist.
var result1 = from o in oldList
              join n in newList on o.Key equals n.Key 
              where o.Value != 0 && n.Value == 0
              select new {Old = o, New = n};

// list of items where weight is not zero and has changed from oldlist.
var result2 = from o in oldList
              join n in newList on o.Key equals n.Key
              where o.Value != 0 && o.Value != n.Value
              select new { Old = o, New = n };