Inheritance

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Inheritance

Def:  The  process  of implementing  the  "Parent-Child" relationship  between  two  or  more classes. As  a  part  of  this  "Inheritance"  implementation,  parent  and  child  classes  are  to  be implemented.

Advantage:  All  the  data  members  and  methods  of  the  parent class are accessible by child class. This is called as "Re-usability". That means the parent class members are re-usable in the child class.

• The parent class can also be called as "Base" / "Super" class.
• The child class can also be called as "Derived" / ―Sub" class.

Classification of Inheritance supported by C#:

1) Implementation Inheritance:

• This is commonly used inheritance.
• Whenever  a  class  is  derived  from  another  class,  it  can  be  called  as  "Implementation Inheritance"
• As said above, all of the members of the super class are adopted by sub class.

2) Interface Inheritance:

• This type of inheritance is taken from "Java".
• Whenever  a  class  is  derived  from  an  interface,  it  can  be  called  as  "Interface Inheritance".
• The  interface  is  similar  to  the  class,  but  doesn‘t  contain  the  method  definitions;  it contains the method declarations only. We discuss about the interfaces in-depth later

Types of Inheritance:

1)  Single Inheritance

• This is the simplest type of inheritance.
• An  inheritance  relationship,  with  only  one  super  class and one sub class

                                               2) Hierarchical Inheritance

An  inheritance  relationship, with  only  one  super  class  and multiple sub classes.

3)  Multi-Level Inheritance

 

• An inheritance relationship, with only one super class  and  multiple  sub  classes,  and  also extended  with  another  sub  class  from  the  first sub class.
• In  other  words,  one  class  acts  as  super  class and sub class simultaneously.

                                            4) Multiple Inheritance

• An  inheritance  relationship, with only multiple super classes and only one sub class.
• "Multiple  Implementation Inheritance"  is  not  supported by  C#,  but "Multiple  Interface Inheritance" is supported by C#.

5)  Hybrid Inheritance

• An inheritance relationship that  contains  a combination  of  any  other two types of inheritances.
• Ex:  Multiple + Hierarchical Inheritance
•        Multiple + Multi Level Inheritance etc.

Note:  Other OOP languages like C++ support multiple inheritance. But C# and  VB.NET doesn‘t 

support  multiple  inheritance  to  avoid  some  practical  problems  while  developing  future  GUI 

applications like windows forms applications, web sites etc.

But instead, C# and VB.NET supports ―multiple interface inheritance‖, because it doesn‘t cause any practical problems.

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