Generic

public class MyList<T>
{
  public void Add(T value)
  {
    // TODO
  }

  public T this[int index]
  {
    get { throw new NotImplementedException(); }
  }
}

var nums = new MyList<int>();
var strs = new MyList<string>();

There are some userful interfaces for the generic. (e.g. IComparable)

public class Utils<T> where T : IComparable
{
  public T Max<T>(T a, T b)
  {
    return a.CompareTo(b) > 0 ? a : b;
  }
}

T can be:

• a value type (where T : struct)
• a reference type (where T : class)
• a class
• an interface
• has a constructor (where T : new())