Can an interface inherit from another interface?-intervew18022012

Yes, an interface can inherit from another interface. It is possible for a class to inherit an interface multiple times, through base classes or interfaces it inherits. In this case, the class can only implement the interface one time, if it is declared as part of the new class. If the inherited interface is not declared as part of the new class, its implementation is provided by the base class that declared it. It is possible for a base class to implement interface members using virtual members; in that case, the class inheriting the interface can change the interface behavior by overriding the virtual members.

Can you create an instance of an interface?
No, you cannot create an instance of an interface.

If a class inherits an interface, what are the 2 options available for that class?
Option 1: Provide Implementation for all the members inheirted from the interface.

namespace Interfaces
{
interface Interface1
{
void Interface1Method();
}

class BaseClass1 : Interface1
{
public void Interface1Method()
{
Console.WriteLine("Interface1 Method");
}
public void BaseClass1Method()
{
Console.WriteLine("BaseClass1 Method");
}
}
}

Option 2: If the class does not wish to provide Implementation for all the members inheirted from the interface, then the class has to be marked as abstract.

namespace Interfaces
{
interface Interface1
{
void Interface1Method();
}

abstract class BaseClass1 : Interface1
{
abstract public void Interface1Method();
public void BaseClass1Method()
{
Console.WriteLine("BaseClass1 Method");
}
}
}

A class inherits from 2 interfaces and both the interfaces have the same method name as shown below. How should the class implement the drive method for both Car and Bus interface?
namespace Interfaces
{
interface Car
{
void Drive();
}
interface Bus
{
void Drive();
}

class Demo : Car,Bus
{
//How to implement the Drive() Method inherited from Bus and Car
}
}

To implement the Drive() method use the fully qualified name as shown in the example below. To call the respective interface drive method type cast the demo object to the respective interface and then call the drive method.

using System;
namespace Interfaces
{
interface Car
{
void Drive();
}
interface Bus
{
void Drive();
}

class Demo : Car,Bus
{
void Car.Drive()
{
Console.WriteLine("Drive Car");
}
void Bus.Drive()
{
Console.WriteLine("Drive Bus");
}

static void Main()
{
Demo DemoObject = new Demo();
((Car)DemoObject).Drive();
((Bus)DemoObject).Drive();
}
}
}