What is the difference between abstract class and interface? Please give an example with scenario when i use abstract class and why? when i use interface?

we can use only one abstract class at a time but multiple interface can be created

• Abstract class methods may have implementation i.e. it may contain non-abstract methods. Interface will not have any kind of implementation in it.
• Scenarios to choose between Interface and Abstract Class:
• To choose Interface : Assume you have 6 functionalities(methods) to be implemented to any Class which implements the interface and you know that the no. of functionalities may increase (suppose 4 new func. which are totally unrelated to existing behaviour, corresponds to multiple inheritance) in  the future. To tackle this , Class C1 : I1{// existing 6 functionalities of Interface I1}Now class C2 has to implement existing 6 and 4 new functionalities.
• So its easy to implement all 10 together in class C2. public class C2 : I1, I2{// 6 func. of I1 and 4 new func. of I2}

To choose Abstract class : to maintain the common behaviour (acquired by base/ abstract class) into the child classes which implements the abstract class.

i will show the code example

public abstract class Employee{

public virtul string FullNamePrint()

{ return "Awais Shabir";

}

}

// Interface Example

Public Interface IEmployee

{string FullNamePrint();

}

if you are using multi inheritance then used interface because interface supports multi inheritance