Compare two Lists and pass to another

Question

I have two List<Int64> ListA contains 10 digits of integer value and ListB contains 6 digits of integer, I have to compare both lists and pass to another List<int64> if ListA contains 6 digits from ListB.

Answer 1

public static void Main(string[] args)
{
    var listA = new List<long>
    {
        1, 2, 3, 4, 5, 6
    };
    var listB = new List<long>
    {
        1, 2, 3, 4, 5, 6, 7, 8, 9, 10
    };

    bool doesListBContainListA = listA.All(numA => listB.Contains(numA));
    var listNew = new List<long>();
    if (doesListBContainListA)
    {
        listNew.AddRange(listA);
        listNew.AddRange(listB);
    }

    Console.WriteLine(string.Join(", ", listNew));
}

The above code will compare if all digits/numbers from listA are contained in listB and if they are they will be added to the new list.

P.S. long is the same as Int64