Inheritance in OOP

Inheritance

One of the most important concepts of object oriented programming is Inheritance. Inheritance is a mechanism of acquiring features and behaviors of one class called as base or parent class into another class called as derived class.

Inheritance implements a IS-A relationship.

Advantages of inheritance

• Code re-usability 
• Reduction in code size
• Improve code readability
• Code extensible support by overriding base class method into derived class  

Disadvantage of inheritance

• Tight coupling between base class and child class
• Performance of your program is affected if inheritance is not implemented properly.
• Many unused data members remain unused & memory is allocated for the same.

Different types of inheritance

• Single Inheritance

When a derived class is created from a single base class.

C# Example

public class Parent

{

    //Definition

}

public class Derived : Parent

{

    //Definition

}

•  Multi-Level Inheritance

When a derived class is created from another derived class is called as multi-level inheritance

C# Example

ppublic class Parent

{

    //Definition

}

public class Derived1 : Parent

{

    //Definition

}

public class Derived2 : Derived1

{

    //Definition

}

• Multiple Inheritance

When a derived class is created from more than one class then it is called as multiple inheritance. This type of inheritance is not supported in C# or .Net

This type of inheritance is not supported in C# or .Net

• Hierarchical Inheritance

When a multiple derived class is created from one single class then it is called as Hierarchical inheritance.

 C# Example

public class Parent

{

    //Definition

}

public class Derived1 : Parent

{

    //Definition

}

public class Derived2 : Parent

{

    //Definition

}

public class Derived3 : Derived1

{

    //Definition

}

public class Derived4 : Derived1

{

    //Definition

}

public class Derived5 : Derived2

{

    //Definition

}

public class Derived6 : Derived2

{

    //Definition

}

• Hybrid Inheritance

This is combination of more than one inheritance. It may be a combination of Multilevel and Multiple inheritance or Hierarchical and Multilevel inheritance or
Hierarchical and Multilevel and Multiple inheritance.

• Why C# does not support multiple inheritance?

C# does not support multiple inheritance because of diamond problem. To know more about diamond problem please refer below link 

https://en.wikipedia.org/wiki/Multiple_inheritance#The_diamond_problem

• As we know multiple inheritance is not supported by C# or .Net what is the other way to achieve multiple inheritance in C# or .Net? 

We can achieve similar functionality using interface in C#.

• Is static class can be inherited ?

Static class can not be inherited. C# complies static class as sealed abstract class hence static class cannot be inherited in c#.

• How to make normal class non inheritable c#?

Using sealed keyword in c# we can stop class from further inheriting it.