Add operation in List

Question

Possible Duplicate:
Merge two object lists with linq

I have 2 Lists of type string:

List1 has items - item1, item2, item3

List2 has items - item1, item4, item5

Now I need to compare both lists and add the missing ones from List2 into List1. The modified List1 will be

list 1 : item1, item2, item3, item4, item5

Answer 1

you can use LiNQ for this:

List<string> newList = List1.Union(List2).ToList();

Answer 2

you can try with this code - Except operator

var result = List2.Except(List1);

foreach(string item in result )
{
   List1.Add(item);
}

Answer 3

I would use linq to do it

var result = List1.Union(List2);

http://msdn.microsoft.com/en-us/library/bb358407.aspx

Return Value Type: System.Collections.Generic.IEnumerable An IEnumerable that contains the elements from both input sequences, excluding duplicates.

Answer 4

A simply way:

foreach(string item in List2)
{
if(!List1.Contains(item))
   List1.Add(item);
}

of course there are shorter (lenght of code) options

Answer 5

You could use LINQ for this.

Look at the Except method and then join the resulting collection to you original collection.

See: http://csharp.net-tutorials.org/category/linq-to-objects/linq-except/