In this part of my C# tutorial we cover public, private, protected, constants, read-only fields, constructors, setters, getters, properties and more on static. I’m taking my time to make sure everyone completely understands object oriented programming in C#. We are getting near the end of the basic syntax and will start doing fun stuff soon.

For best results print the code below and write out your own notes in your own words and use that as a cheat sheet.

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Code & Transcript

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

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

// We cover public, private, protected, constants,
// read-only fields, constructors, setters, getters, 
// properties and more on static

namespace CSharpTutA.cs
{
    class Animal
    {
        // Define fields that are protected with private
        // Private fields can only be accessed by
        // methods in the class and they are not 
        // accessible by subclasses
        // protected fields can only be accessed by
        // methods in the class and by subclasses
        private string name;
        private string sound;

        // You can define constants
        public const string SHELTER = "Derek's Home for Animals";

        // You can define read-only fields that are set
        // at runtime in constructors, but then can't
        // be changed
        public readonly int idNum;

        // Method (Capabilities)
        public void MakeSound()
        {
            Console.WriteLine("{0} says {1}",
                name, sound);
        }

        // Default constructor
        public Animal() 
        :this("No Name", "No Sound") { }

        // Constructor called if only name is passed
        // this passes the parameters to the next
        // constructor
        public Animal(string name)
            : this(name, "No Sound") { }

        // Constructor that receives parameters
        public Animal(string name,
            string sound)
        {
            SetName(name);
            Sound = sound;

            // Increment the number of animals
            // property
            NumOfAnimals = 1;

            // Define the read-only value which is
            // the same for all Animals
            Random rnd = new Random();
            idNum = rnd.Next(1, 2147483640);
        }

        // Setters (Mutators) protect the fields 
        // from receiving bad data
        public void SetName(string name)
        {
            // Any checks if any character in the string 
            // is a number and if so returns true
            // Since we won't allow numbers we will 
            // protect our data
            if (!name.Any(char.IsDigit))
            {
                this.name = name;
            } else
            {
                // We have this duplicated code because 
                // everything isn't a property
                this.name = "No Name";
                Console.WriteLine("Name can't contain numbers");
            }
        }

        // Getters (Accessors) can provide output
        // aside from the value stored
        public string GetName()
        {
            return name;
        }

        // The preferred way to define getters and
        // setters is through properties
        public string Sound
        {
            get { return sound; }
            set
            {
                // value is assigned the value passed in
                if (value.Length > 10)
                {
                    sound = "No Sound";
                    Console.WriteLine("Sound is too long");
                } else
                {
                    sound = value;
                }
            }
        }

        // You can have the getters and setters
        // generated for you like this and also
        // set the default value
        public string Owner { get; set; } = "No Owner";

        // You can also define static properties
        public static int numOfAnimals = 0;

        public static int NumOfAnimals
        {
            get { return numOfAnimals; }
            set { numOfAnimals += value; }
        }

    }
}

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

using System;

namespace CSharpTutA.cs
{
    class Program
    {

        static void Main(string[] args)
        {
            Animal cat = new Animal();

            // Call the setter
            cat.SetName("Whiskers");

            // Set the property
            cat.Sound = "Meow";

            Console.WriteLine("The cat is named {0} and says {1}",
                cat.GetName(), cat.Sound);

            // Test auto generated getters and setters
            cat.Owner = "Derek";

            Console.WriteLine("{0} owner is {1}",
                cat.GetName(), cat.Owner);

            // Get the read-only id number
            Console.WriteLine("{0} shelter id is {1}",
                cat.GetName(), cat.idNum);

            // Test static property
            Console.WriteLine("# of Animals : {0}",
                Animal.NumOfAnimals);


            Console.ReadLine();

        }
        
    }

}