Answers for "what is an abstract class in c#"

class in c#

public class Car
{  
    // fields
    public bool isDriving = false;
    
    // constructor
    public Car( string make )
    {
        Make = make;
    }
	
    // properties
    private string _make = string.Empty;
    public string Make
    {
        get { return _make; }
        set { _make = value; } 
    }
    
    // methods
    public void drive()
    {
        if( isDriving )
        {
			// Car is already moving
        }
        else
		{
            // start driving the car
            isDriving = true;
    	}        
    }

    public void stop()
    {
		if( isDriving )
		{
			// stop the car 
			isDriving = false;
		}
        else
        {
			// car is already not moving
        }        
    }      
}

// ---
// An example of using this class in a console app

using System;
					
public class Program
{
	public static void Main()
	{		
        // construct a new class of type Car and set the Make
      	// property to "VW" using the constructor.
		Car newCar = new Car( "VW" );
		
      	// display the make of our new car
		Console.WriteLine( newCar.Make );
		
      	// call the drive method of the car class
		newCar.drive();		
		
      	// display the value of the isDriving property to
		Console.WriteLine( newCar.isDriving );
		
      	// call the stop method of the car class
		newCar.stop();
		
      	// display the value of the isDriving property
		Console.WriteLine( newCar.isDriving );
	}
}

// the class 
public class Car
{  
    // fields
    public bool isDriving = false;
    
    // constructor w
    public Car( string make )
    {
        Make = make;
    }
	
    // properties
    private string _make = string.Empty;
    public string Make
    {
        get { return _make; }
        set { _make = value; } 
    }
    
    // methods
    public void drive()
    {
        if( isDriving )
        {
        		// Car is already moving
        }
        else
		{
            // start driving the car
            isDriving = true;
    	}        
    }

    public void stop()
    {
		if( isDriving )
		{
			// stop the car 
			isDriving = false;
		}
        else
        {
			// car is already not moving
        }        
    }      
}

c# abstract class and interfaces

// ------------------- ABSTRACT vs INTERFACES ------------------------ //
// Both are used to define the architecture of the application


// ---------- ABSTRACT CLASS --------- //
// -> The methods can have an implementation (be defined)
// -> It's elements are private by default
// -> It can contain fields
// -> It can inherit from another abstract class or interface 
// -> It can have abstract and non-abstract methods. The abstract classes have to be implemented in the child class. 

public abstract class AbsParent { 
  
  	private int count = 0;
  
    public void foo1()    
    {
    	Console.WriteLine("Hi there, I'm a normal method that will be inherited!");
    }
  
    public abstract void foo2();  // You can't have an implementation for this abstract method 
  
    public virtual void foo3()    
    {
    	Console.WriteLine("Hi there, I'm a virtual method!");
    }  
} 


// --------- INTERFACES --------- //
// -> It's not a class, it's an entity
// -> The methods can't have an implementation
// -> It's elements are public by default and can't have acesso modifiers 
// -> It can't contain fields like for example, "private int count", but it can contain properties 
// -> It can only inherit from another interface 
// -> A class can inherit from multiple interfaces
// -> A class inheriting from an interface, has to implement all it's methods 

public interface IParent { 
  
  string myProterty{get; set;} 
  
  void foo1(); // You can't have an implementation for these methods
  void foo2(); 
  
} 



// -------- INHERITANCES --------- // 

// class 'AbsParent' inherit in child class 'Child1' 
public class Child1 : AbsParent { 
  
    public override void foo2()    // The implementation of the AbsParent abstract methods is mandatory 
    { 
        Console.WriteLine("Only in the child/derived class, can I be defined!"); 
    } 
    
  
  	public override void foo3() 
    { 
        Console.WriteLine("Class name is Child1"); 
    } 
} 
  

// class 'IParent' inherit in another child class 'Child2' 
public class Child2 : IParent { 
 
    public void foo1()    // The implementation of all the IParent methods is mandatory 
    { 
        Console.WriteLine("Only in the child/derived class, can I be defined!"); 
    } 
    
  
  	public void foo2() 
    { 
        Console.WriteLine("Only in the child/derived class, can I be defined!"); 
    } 

} 



// ---------- MAIN --------- //
public class main_method { 
  
    // Main Method 
    public static void Main() 
    { 
        AbsParent obj = new AbsParent();  // ERROR!! You can't create an object of an abstract class
                                          // it is used only for inheritance purposes. The same logic 
                                          // goes to interfaces.
    } 
}