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Posts Tagged ‘order’

Simple invoking order of Constructors

Posted by Paul on December 16, 2010

In this article I am trying to show the order in which constructor and destructors are called for a class and its base class.


It is of great importance that we should know constructors work in an inherited manner – especially in interviews.

This will give us more clarity in creating or destroying objects in constructors/destructors.


We have a class named ChildClass having a constructor and destructor

Also, a class named ParentClass having a constructor and destructor


Whenever the constructor or destructor is called it logs a message to the main form.


We create an instance of ChildClass and make Garbage Collector to destroy the instance.

Thus we are able to invoke the entire constructors/destructors involved.

new ChildClass();


We are able to see the result like: Even though we are creating the instance of ChildClass the ParentClass constructor is invoked first.

But while on destruction the ChildClass destructor is invoked first.


Class: ParentClass

public class ParentClass


    public ParentClass()


        MainForm.AddMessage("ParentClass constructor invoked");





        MainForm.AddMessage("ParentClass destructor invoked");



Class: ChildClass


public class ChildClass : ParentClass


    public ChildClass()


        MainForm.AddMessage("ChildClass constructor invoked");





        MainForm.AddMessage("ChildClass destructor invoked");





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