Inheritence in C#

Multiple inheritence is not supproted by C#. But there is a solution to this using interfaces. Lets see how as explained by Ms. Asha Bora.

We know inheriting from a class is a powerful mechanism, but the real power of inheritance comes from inheriting from an interface.
Interface allows you to truly separate the "what" from "how". The interface tells what the name is, return type and parameter of the method are. Exactly how the method is implemented is not a concern of the interface. It represent how you want an object to be represent rather then how it happens to be implemented in a particular moment.

Syntax to declare interface: To declare the interface we use the interface keyword.
Eg:
interface IComparable
{
int xyz();
}

Points to be noted about Interface:

• Interface should not contain any variable.
• Interface should not have any constructor. Since a constructor contains the statements to initialize the variable of an object, but interface does not contain any variable.
• A Destructor is also not allowed in an interface. Since it contain the statement to destroy the object instance.
• No need to supply the access specifier to the methods. Since all the methods are public by default in an interface.
• We cannot nest any types like enums , class, structs, interfaces, delegates inside an interface.
• A class which implements an interface needs to implements all the members of the interface.

A class can inherit from a single class but can implement from multiple interfaces. An interface can inherit multiple interfaces. So we say that in C# multiple inheritance is applicable only through Interfaces, but not via classes.
A class or structure that implements an interface also implements the base interface of its inherited interface.
A class can extend another class and implement an interface at the same time. The base class is named first followed by a comma, followed by the interface.
eg:
class Defaultclass
{
…
}
class XYZ: Defaultclass, IComparable
{
...
}

Inheriting interface: we have declared an interface in the above example called IComparable, the below examples shows how a interface inherit another interface…
interface IOrder : IComparable
{
void abc();
}