//  Author  : Tech Point Fundamentals

//  Website : www.techpointfunda.com

//  Demo    : Constructors in C#

​

using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("\n--------- Default Constructor --------- ");

        var _userDefault = new User();      

        Console.WriteLine("UserName : " + _userDefault.UserName);

        Console.WriteLine("Password : " + _userDefault.Password);

        Console.WriteLine("\n\n--------- Parameterized Constructor --------- ");

        var _userParameterized = new User("TechPoint", "********");         

        Console.WriteLine("UserName : " + _userParameterized.UserName);

        Console.WriteLine("Password : " + _userParameterized.Password);

        Console.WriteLine("\n\n--------- Copy Constructor --------- ");

        var _userCopy = new User(_userParameterized);       

        Console.WriteLine("UserName : " + _userCopy.UserName);

        Console.WriteLine("Password : " + _userCopy.Password);

        Console.WriteLine("\n\n--------- OUT and REF Parameterized Constructor --------- ");

        string _refParameter = "REF parameter";

        string _outParameter;

        var _userParam = new User(out _outParameter, ref _refParameter);        

        Console.WriteLine("OUT Parameter : " + _outParameter);

        Console.WriteLine("REF Parameter : " + _refParameter);                  

        Console.WriteLine("\n\n--------- Structure with Constructor --------- ");

        var _struct = new MyStructure("MyInputParameter");      

        var _structOptional = new MyStructure(10);

        Console.WriteLine("\n\n--------- Private Constructor --------- ");

        var _superAdmin = new SuperAdmin("Dashboard","********");

        Console.WriteLine("AccessArea : " + _superAdmin.AccessArea);

        Console.WriteLine("AccessCode : " + _superAdmin.AccessCode);

        Console.WriteLine("AccessToken : " + SuperAdmin.AccessToken);

        Console.WriteLine("\n\n--------- Constructor Chaining--------- ");

        var _constructorChain = new SuperAdmin("********");

        Console.WriteLine("AccessArea : " + _constructorChain.AccessArea);

        Console.WriteLine("AccessCode : " + _constructorChain.AccessCode);

        Console.WriteLine("AccessToken : " + SuperAdmin.AccessToken);

        Console.WriteLine("\n\n--------- Constructor with Exception --------- ");

        var _superAdminObject = new SuperAdmin("ProfitAndLossReport","");

        Console.WriteLine("AccessArea : " + _superAdmin.AccessArea);

        Console.WriteLine("AccessCode : " + _superAdmin.AccessCode);

        Console.WriteLine("AccessToken : " + SuperAdmin.AccessToken);

    }

    private Program()

    {

        Console.WriteLine("Private constructor of Program class is called.");   

    }

}

​

public class User

{

    // Static Constructor

    static User()

    {

        Console.WriteLine("Static Constructor of User class is called.");

    }

    // User Defined Default Constructor (Parameterless Constructor)

    public User()

    {

        Console.WriteLine("User defined Default constructor of User class is called.");

        this.UserName = "UnKnown";

        this.Password = "*****";

    }

    // Parameterized Constructor : Constructor Overloading

    public User(string userName, string password)

    {

        Console.WriteLine("Parameterized Constructor of User class is called.");

        this.UserName = userName;

        this.Password = password;

    }

    // Copy Constructor

    public User(User user)

    {

        Console.WriteLine("Copy Constructor of User class is called.");

        this.UserName = user.UserName;  

        this.Password = user.Password;  

    }   

    public string UserName {get; set;}

    public string Password {get; set;}

    public User(out string outParameter, ref string refParameter)

    {       

        Console.WriteLine("Parameterized constructor of User class with OUT and REF type parameter is called.");

        outParameter = "OUT Parameter of User Class"; 

        refParameter = "REF Parameter of User Class";

    }

}

// Abstract Class

public abstract class BaseClass

{

    // Constructor with params parameter

    public BaseClass(params string[] input)

    {

        Console.WriteLine("Base Abstract Class params Parameterized Constructor is called.");

    }

    public BaseClass(string x)

    {

        Console.WriteLine("Base Abstract Class Constructor is called.");

    }

}

​

public class SuperAdmin : BaseClass

{

    private static string _token = null;

    // Private Constructor

    private SuperAdmin() : base() // Here base is optional

    {

        Console.WriteLine("Private Constructor of SuperAdmin class is called.");

        if(String.IsNullOrWhiteSpace(this.AccessArea))

        {

            Console.WriteLine("Default Access Area is allocated");

            this.AccessArea = "Reports";

        }

        if(String.IsNullOrWhiteSpace(this.AccessCode))

        {

            Console.WriteLine("Please provide vaild AccessCode.");

            return; // Return without any value

        }           

    }

    public SuperAdmin(string accessCode) : this()

    {

        Console.WriteLine("Public Constructor of SuperAdmin class is called. Which initiate the constructor chaining.");        

        this.AccessCode = accessCode;

        // Calling class method in the constructor

        _token = GetToken(this.AccessArea, this.AccessCode);

    }

    public SuperAdmin(string accessArea, string accessCode)

    {

        Console.WriteLine("Public Constructor of SuperAdmin class is called.");

        this.AccessArea = accessArea;

        this.AccessCode = accessCode;

        if(String.IsNullOrWhiteSpace(this.AccessCode))

        {

            throw new Exception("Please provide vaild AccessCode.");            

        }   

        // Calling class method in the constructor

        _token = GetToken(this.AccessArea, this.AccessCode);

    }

    public string AccessArea {get; set;}

    public string AccessCode {get; set;}

    public static string AccessToken {get { return _token;}}

    private string GetToken(string area, string code)

    {

        // Logic to generate token

        return "Access Token Generated Successfully for : " + area;

    }

}

​

public struct MyStructure

{

    // Static Constructor

    static MyStructure()

    {

        Console.WriteLine("Static Constructor of structure is called.");

    }

    // Parameterized Constructor 

    public MyStructure(string inputParameter)

    {

        Console.WriteLine("Parameterized Constructor of structure is called with value : " + inputParameter);       

    } 

    public MyStructure(int inputParameter1, string optionalParameter = "")

    {

        Console.WriteLine("Optional Parameterized Constructor of structure is called with value : " + inputParameter1);     

    } 

}