C# Online Compiler | .NET Fiddle

// 	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);		
	} 
}

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

Compilation error (line 11, col 7): Operator '==' cannot be applied to operands of type 'int' and 'string'