Difference between revisions of "OOP Class12"

Revision as of 03:28, 24 November 2015

Interfaces Part2

There are many interfaces in the .net framework. Some that we have been working with are the [ICollection https://msdn.microsoft.com/en-us/library/system.collections.icollection(v=vs.110).aspx] [IList https://msdn.microsoft.com/en-us/library/system.collections.ilist(v=vs.110).aspx] and [IEnumerable https://msdn.microsoft.com/en-us/library/system.collections.ienumerable(v=vs.110).aspx]

These interfaces allow us to use methods in a List and Array.

Here is an example of sorting a list of ints or an int[] <csharp> int[] ints = new int[] { 5, 4, 2, 3, 1 };

           foreach (var number in ints)
           {
               Console.Write(string.Format("{0}\t", number));
           }
           Console.WriteLine();

           Array.Sort(ints);
           foreach (var number in ints)
           {
               Console.Write(string.Format("{0}\t", number));
           }
           Console.WriteLine();
           
           ints = ints.Reverse().ToArray();
           foreach (var number in ints)
           {
               Console.Write(string.Format("{0}\t", number));
           }
           Console.WriteLine();

                       //mess it up again
           ints = new int[] { 5, 4, 2, 3, 1 };

           ints = ints.OrderBy(i => i).ToArray();
           foreach (var number in ints)
           {
               Console.Write(string.Format("{0}\t", number));
           }
           Console.WriteLine();

           //mess it up again
           ints = new int[] { 5, 4, 2, 3, 1 };

           //last way slightly uses agregate function to Order array by int, turns array into list so we can call foreach
           ints.OrderBy(i => i).ToList().ForEach(ii=>Console.Write(string.Format("{0}\t", ii)));
           Console.WriteLine();

</csharp>

now with List <csharp> </csharp>

Now lets sort some dogs <csharp> class Dog : IComparable

   {
       public string Name;
       protected int age;

       public int Age { get { return age; } set { age = value; } }

       public int Weight;
       public string BarkSound;

       public Dog()
       {
           this.Name = "fido";
           this.BarkSound = "woof!";
           this.Weight = 1;
       }

       public string About()
       {
           return string.Format("Hello my name is {0}. I'm {1} years old. I weigh {2} lbs", this.Name, this.Age, this.Weight);
       }

       public int CompareTo(object obj)
       {
           if (obj is Dog)
           {
               if (this.Age > ((Dog)obj).Age) return 1;
           }
           return 0;
       }

} </csharp>

and finally override some operators <csharp> public static int Compare(Dog left, Dog right)

       {
           if (object.ReferenceEquals(left, right))
           {
               return 0;
           }
           if (object.ReferenceEquals(left, null))
           {
               return -1;
           }
           return left.CompareTo(right);
       }

       public static bool operator <(Dog left, Dog right)
       {
           return (Compare(left, right) < 0);
       }
       public static bool operator >(Dog left, Dog right)
       {
           return (Compare(left, right) > 0);
       }

</csharp>

Home work

Toastable project in moodle

Make one of your classes sortable by implementing IComparable