I cover a bunch of cool things you can do with C# in this tutorial. We’ll learn about IEnumerable, Indexer, Enumerator, Operator Overloading, Custom Casting, Anonymous Types and more.

For best results take notes on the cheat sheet provided below as you watch and leave any questions you have.

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Code & Transcript

// ---------- Animal.cs ----------

namespace CSharpTutA.cs
{
    class Animal
    {
        public string Name { get; set; }

        public Animal(string name = "No Name")
        {
            Name = name;
        }
    }
}

// ---------- AnimalFarm.cs ----------

using System.Collections;
using System.Collections.Generic;

namespace CSharpTutA.cs
{
    // IEnumerable provides for iteration 
    // over a collection
    class AnimalFarm : IEnumerable
    {
        // Holds list of Animals
        private List<Animal> animalList = new List<Animal>();

        public AnimalFarm(List<Animal> animalList)
        {
            this.animalList = animalList;
        }

        public AnimalFarm()
        {
        }

        // Indexer for AnimalFarm created with this[]
        public Animal this[int index]
        {
            get { return (Animal)animalList[index]; }
            set { animalList.Insert(index, value); }
        }

        // Returns the number of values in the 
        // collection
        public int Count
        {
            get{
                return animalList.Count;
            }
        }

        // Returns an enumerator that is used to 
        // iterate through the collection
        IEnumerator IEnumerable.GetEnumerator()
        {
            return animalList.GetEnumerator();
        }


    }
}

// ---------- Box.cs ----------

using System;

namespace CSharpTutA.cs
{
    class Box
    {
        public double Length { get; set; }
        public double Width { get; set; }
        public double Breadth { get; set; }

        public Box() 
        :this(1,1,1) { }

        public Box(double l,
            double w,
            double b)
        {
            Length = l;
            Width = w;
            Breadth = b;
        }

        public static Box operator +(Box box1, Box box2)
        {
            Box newBox = new Box()
            {
                Length = box1.Length + box2.Length,
                Width = box1.Width + box2.Width,
                Breadth = box1.Breadth + box2.Breadth
            };
            return newBox;
        }

        // Through operator overloading you can
        // allow users to interact with your
        // custom objects in interesting ways
        // You can overload +, -, *, /, %, !,
        // ==, !=, >, <, >=, <=, ++ and --
        public static Box operator -(Box box1, Box box2)
        {
            Box newBox = new Box()
            {
                Length = box1.Length - box2.Length,
                Width = box1.Width - box2.Width,
                Breadth = box1.Breadth - box2.Breadth
            };
            return newBox;
        }

        public static bool operator ==(Box box1, Box box2)
        {
            if((box1.Length == box2.Length) &&
                (box1.Width == box2.Width) &&
                (box1.Breadth == box2.Breadth))
            {
                return true;
            }
            return false;
        }

        public static bool operator !=(Box box1, Box box2)
        {
            if ((box1.Length != box2.Length) ||
                (box1.Width != box2.Width) ||
                (box1.Breadth != box2.Breadth))
            {
                return true;
            }
            return false;
        }

        // You define how your object is converted
        // into a string by overridding ToString
        public override string ToString()
        {
            return String.Format("Box with Height : {0} Width : {1} and Breadth : {2}",
                Length, Width, Breadth);
        }

        // You can convert from a Box into an
        // int like this even though this
        // wouldn't make sense
        public static explicit operator int(Box b)
        {
            return (int)(b.Length + b.Width + b.Breadth) / 3;
        }

        // Convert from an int to a Box
        public static implicit operator Box(int i)
        {
            // Return a box with the lengths all
            // set to the int passed
            return new Box(i, i, i);
        }

    }
}

// ---------- Program.cs ----------

using System;
using System.Linq;
using System.Collections.Generic;

namespace CSharpTutA.cs
{
    // Indexers allow you to access items
    // like arrays

    class Program
    {

        static void Main(string[] args)
        {
            // Create an AnimalFarm object
            AnimalFarm myAnimals = new AnimalFarm();

            // Add Animals
            myAnimals[0] = new Animal("Wilbur");
            myAnimals[1] = new Animal("Templeton");
            myAnimals[2] = new Animal("Gander");
            myAnimals[3] = new Animal("Charlotte");

            foreach(Animal i in myAnimals)
            {
                Console.WriteLine(i.Name);
            }

            // Testing operator overloading
            Box box1 = new Box(2, 3, 4);
            Box box2 = new Box(5,6,7);

            Box box3 = box1 + box2;

            // Converts the box to a string with
            // ToString
            Console.WriteLine($"Box 3 : {box3}");

            Console.WriteLine($"Box Int : {(int)box3}");

            // Convert an int into a Box
            Box box4 = (Box)4;

            Console.WriteLine($"Box 4 : {(Box)4}");

            // Sometimes you want to build a simple
            // class that contains fields and
            // Anonymous types are great for that
            var shopkins = new { Name = "Shopkins", Price = 4.99 };

            Console.WriteLine("{0} cost ${1}",
                shopkins.Name, shopkins.Price);

            // Anonymous types can also be stored 
            // in an array

            var toyArray = new[] { new {
                Name = "Yo-Kai Pack", Price = 4.99 },
                new { Name = "Legos", Price = 9.99 } };

            // You can loop through the array
            foreach(var item in toyArray)
            {
                Console.WriteLine("{0} costs ${1}",
                    item.Name, item.Price);
            }

            Console.WriteLine();

            Console.ReadLine();

        }

    }

}