Inheritance Example (Social Media Demo)

using System;

namespace SocialMedia
{
    class Program
    {
        static void Main(string[] args)
        {
            Post post1 = new Post("Thanks for the Birthday Wishes", true, "Jason");
            Console.WriteLine(post1.ToString());
            ImagePost imagePost1 = new ImagePost("Check out my new shoes", "Jason",
                "https://images.com/newshoes.jpg", true);
            Console.WriteLine(imagePost1);

            Console.ReadLine();
        }
    }

    class Post
    {
        private static int currentPostId;

        // properties
        protected int ID { get; set; }
        protected string Title { get; set; }
        public string SendByUserName { get; set; }
        public bool IsPublic { get; set; }

        // Default constructor. If a derived class does not invoke a base class constructor
        // explicitly, the default constructor is called implicitly.

        public Post()
        {
            ID = 0;
            Title = "My First Post";
            IsPublic = true;
            SendByUserName = "Jason Young";
        }

        // Instance constructor that has three parameters
        public Post(string title, bool isPublic, string sendByUsername)
        {
            this.ID = GetNextID();
            this.Title = title;
            this.SendByUserName = sendByUsername;
            this.IsPublic = isPublic;
        }

        protected int GetNextID()
        {
            return ++currentPostId;
        }

        public void Update(string title, bool isPublic)
        {
            this.Title = title;
            this.IsPublic = isPublic;
        }

        //Virtual method override of the ToString method that is inherited from System.Object
        public override string ToString()
        {
            return String.Format("{0} - {1} - by {2}", this.ID, this.Title, this.SendByUserName);
        }

    }

    //ImagePost derives form Post and adds a property (ImageURL) and two constructors
    class ImagePost:Post
    {
        public string ImageURL { get; set; }

        public ImagePost() { } // Constructor

        public ImagePost(string title, string sendByUsername, string imageURL, bool isPublic)
        {
            this.ID = GetNextID();                  // these methods are inherited from the Post class
            this.Title = title;
            this.SendByUserName = sendByUsername;
            this.IsPublic = isPublic;

            this.ImageURL = imageURL;               // this method is unique to ImagePost class
        }

        //Virtual method override of the ToString method that is inherited from System.Object
        public override string ToString()
        {
            return String.Format("{0} - {1} - {2} - by {3}", this.ID, this.Title, this.ImageURL, this.SendByUserName);
        }
    }
}