How constructors are called while the classes are inherited: Exploring Object Oriented Programming and Concepts

Constructor Calls in Inheritance

Case study 1:

ClassA is a base class of ClassB.

Both classes have default constructor.

Observations:
While creating a new instance of ClassB (without parameters):
- it will first call default constructor of ClassB which will call constructor of ClassA.
- it will complete executing code of default constructor of ClassA.
- after that, it will complete executing code of default constructor of ClassB.

Case study 2:

ClassA is a base class of ClassB.

ClassA has no default constructor, but only parameterized constructor.
ClassB has a default constructor.

Observations: 
- it will not allow creating ClassA without a default constructor 

- if you want to do so, you need to call a base class constructor from ClassB's constructor: 

For example, following is the constructor of class A 

public ClassA(string someVariable) { ..... some code .... }  

To allow ClassA without a default constructor, its all child classes should call base class constructor as below: 

public ClassB(): base("some value") 

or

public ClassB(string fullName): base(fullName)