Non-standard joining of two lists

Question

I have two lists: list1 and list2. I want to join the lists in a way that the values in list1 should not be affected, even if it contains duplicate values. However, when appending values from list2 the duplicate values should not be removed.

I had tried Union, which will distinct all the values and eliminate my repeated values in list1.

For example

list1 = [a, b, c, c, d, e] 
list2 = [a,c,f,g] 
my required solution 
list3=[a, b, c, c, d, e, f, g]

Can you post the relevant code so everyone can have a look at where you're going wrong — Izzy, Sep 12 '14 at 10:14
[`.Concat()`](http://msdn.microsoft.com/ru-ru/library/bb302894(v=vs.110).aspx) — Artyom Neustroev, Sep 12 '14 at 10:15
http://stackoverflow.com/questions/1528171/joining-two-lists-together Can you clarify your question? I can't seem to pick it up. — Irvin Denzel Torcuato, Sep 12 '14 at 10:15
for example list1 = [a, b, c, c, d, e] list2 = [a,c,f,g] my required solution list3=[a, b, c, c, d, e, f, g] — niXy, Sep 12 '14 at 10:17
@ArtyomNeustroev Concat will just join two list. I have Specific requirement — niXy, Sep 12 '14 at 10:21
It really helps if you just try to think of a way to do that on paper or just describe the algorithm, e.g. *I start with copying the first list. Then for each item in the second list I do ....*. — Dirk, Sep 12 '14 at 10:22

score 1 · Answer 1 · answered Sep 12 '14 at 10:22

1

var list3 = list1.ToList();
foreach (var val in list2)
{
    if (!list3.Contains(val))
        list3.Add(val);
}

This would give you a new list with all the values from list1 and list2.

answered Sep 12 '14 at 10:22

Mr Jones

134
7

Which is not what the author of the question wants. – Dirk Sep 12 '14 at 10:23

score 1 · Accepted Answer · answered Sep 12 '14 at 10:22

1

var MyList = List1.Concat(List2.Except(List1).ToList());

answered Sep 12 '14 at 10:22

David Pilkington

13,528
3
41
73

score 0 · Answer 3 · answered Sep 12 '14 at 10:29

0

You would want to use something like this

var list1 = new List<int> {1, 2, 3, 3}; 
var list2 = new List<int> {1, 2, 3, 4, 5, 3};
var list3 = list1.Concat(list2.Except(list1)); // 1, 2, 3, 3, 4, 5

answered Sep 12 '14 at 10:29

oleksii

35,458
16
93
163

Non-standard joining of two lists

3 Answers3