Using HashSet<int> to create an integer set

Question

I want to create an class that represents an integer set using a HashSet<int>. I want it to keep track of which values are included in the set using that internal container. I've done this so far:

class SetInteger
{
    HashSet<int> intTest= new HashSet<int>();
    intTest.Add(1);
    intTest.Add(2);
    intTest.Add(3);
    intTest.Add(4);
    intTest.Add(5);
    intTest.Add(6);
    intTest.Add(7);
    intTest.Add(8);
    intTest.Add(9);
    intTest.Add(10);
}

So, here I think I'm adding some values to the HashSet, but I dont see how this can keep track of which values that are included in the set. Any ideas?

Answer 1

The hash set has a Contains method that allows you to check whether a value is in the set.

In addition, the HashSet<T> implements the ISet<T> interface and therefore provides many methods for working with sets, such as union, intersection and determining if a set of values is a (proper) super- or subset of your set.

HashSet<int> intTest = new HashSet<int>()
{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

bool has4 = intTest.Contains(4);    // Returns true
bool has11 = intTest.Contains(11);  // Returns false
bool result = intTest.IsSupersetOf(new []{ 4, 6, 7 }); // Returns true

_{By the way, did you know about the collection initializer syntax?}

---

You can also foreach on the set to get each element it contains (in an unspecified order):

foreach(int value in intTest)
{
    // Do something with value.
}

Or convert it to an array or mutable list (also in an unspecified order):

int[] arr = intTest.ToArray();
List<int> lst = intTest.ToList();