How to get difference between two list in C#?

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Hi All

I have two List I wanted to get difference of two list in 3rd list. my 1st list null able.

What I have tried:

List<long?> RateCardList = new List<long?>();
                List<long> categorylist = new List<long>();

C#

List<long?> ThirdList = new List<long?>();

ThirdList = RateCardList.Except(categorylist);

I am getting error in ThirdList

Posted 23-Aug-17 19:45pm

murkalkiran

Updated 23-Aug-17 19:57pm

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Thomas Daniels · Accepted Answer · 2017-08-23T19:57:00

Solution 1

You get the error because your argument to Except has long values, as opposed to RateListCard, that holds long?s.

Do this:

C#

ThirdList = RateCardList.Except(categoryList.Select(x => new long?(x)));

.Select(x => new long?(x)) takes all elements, calls the code to make them long?s and returns a new IEnumerable<long?>, which you can validly pass to Except.

Posted 23-Aug-17 19:57pm

Thomas Daniels

Comments

Richard Deeming 25-Aug-17 14:23pm

It might be marginally simpler to use Cast instead of Select:

.Except(categoryList.Cast<long?>())