Two ArrayList manipulation

Question

I have one ArrayList in Session, lets say for example [305,306,380].

On submit, user choice other products which i save them in 2nd array, for example [390,305,480,380]

How can i make another three arrays where

1. All new values [390,480]

2. All values which are in both lists [305,380]

3. All values from list1 which are not in list2 [306]

I need this in ASP.NET 4.0 C#

Answer 1

You can use ArrayList.ToArray() to get arrays against your arraylists. Then using LINQ you can easily get what you want withExcept an Intersect methods, for example

array2.Except(array1)
array1.Except(array2)
array1.Intersect(array2)

Edit: Complete Code

According to your requirement, your code may look-like this;

        ArrayList arrayList1 = new ArrayList(new int[] { 305, 306, 380 });
        ArrayList arrayList2 = new ArrayList(new int[] { 390, 305, 480, 380 });

        int[] array1 = (int[])arrayList1.ToArray(typeof(int));
        int[] array2 = (int[])arrayList2.ToArray(typeof(int));

        //1. All New values
        int[] uniqueInArray2 = array2.Except(array1).ToArray();

        //2. Common values
        int[] commonValues = array1.Intersect(array2).ToArray();

        //3. Values of arrayList1 which are not in arrayList2
        int[] uniqueInArray1 = array1.Except(array2).ToArray();

Answer 2

Use HashSet the folowing way:

var first = new HashSet<int>();
first.Add(...);

var second = ...;

1. second.ExceptWith(first);
2. first.IntersectWith(second);
3. first.ExceptWith(second);