Introduction

In this blog, we will learn about the constructor, types of constructor, and the destructor in C++ language.

Let's start!

What is constructor?

C++ compiler provides a special kind of member function for initialization of objects. This function is called the constructor.

Types of constructor

Before creating a constructor, always remember the below points.

Default Constructor

A constructor that accepts no parameter is called the default constructor.

Example

  1. // default constructor example
  2. #include<iostream.h>
  3. #include<conio.h>
  4. class emp
  5. {
  6. int id,sal; //member variable
  7. public:
  8. emp() //default constructor
  9. {
  10. id=1;
  11. sal=2000;
  12. }
  13. void display() // member function for display data
  14. {
  15. cout<<"Employee id: "<<id<<endl;
  16. cout<<"Employee salary: "<<sal<<endl;
  17. }
  18. };
  19. void main()
  20. {
  21. emp obj;
  22. obj.display();
  23. getch();
  24. }

Parameterized Constructor

A constructor that takes at least one argument is called parameterized constructor.

Example

  1. //parameterized constructor
  3. #include<iostream.h>
  4. #include<conio.h>
  5. class emp
  6. {
  7. int id,sal; //member variable
  8. public:
  9. emp(int empId,int empSal) //parameterized constructor
  10. {
  11. id=empId;
  12. sal=empSal;
  13. }
  14. void display() //member function
  15. {
  16. cout<<"Employee id: "<<id<<endl;
  17. cout<<"Employee salary: "<<sal<<endl;
  18. }
  19. };
  20. void main()
  21. {
  22. emp obj(1,3000); //passing constructor argument value
  23. obj.display();
  24. getch();
  25. }

Copy Constructor

A constructor that is used for initializing an object from another object is called copy constructor.

Example

  1. //copy constructor
  3. #include<iostream.h>
  4. #include<conio.h>
  5. class emp
  6. {
  7. int id,sal;
  8. public:
  9. emp(int empId,int empSal) //paramereized constructor
  10. {
  11. id=empId;
  12. sal=empSal;
  13. }
  14. emp(emp &em) //copy constructor
  15. {
  16. id=em.id;
  17. sal=em.sal;
  18. }
  19. void display() //member function
  20. {
  21. cout<<"\nEmployee id: "<<id<<endl;
  22. cout<<"Employee salary: "<<sal<<endl;
  23. }
  24. };
  26. void main()
  27. {
  28. emp obj(1,2000);
  29. emp obj1(obj);
  31. obj.display();
  32. obj1.display();
  33. getch();
  34. }

What is destructor?

A destructor is used for destroying the objects that have been created by the constructor.

Before creating a destructor, always remember the below points.

Example

  1. // destructor example
  3. #include<iostream.h>
  4. #include<conio.h>
  5. class emp
  6. {
  7. int id,sal;
  8. public:
  9. emp() //default constructor
  10. {
  11. id=1;
  12. sal=5000;
  13. }
  14. ~emp() //destructor
  15. {
  16. cout<<"Ok Bye for now...";
  17. }
  18. void display() //member function
  19. {
  20. cout<<"Employee id: "<<id<<endl;
  21. cout<<"Employee salary: "<<sal<<endl;
  22. }
  23. };
  24. void main()
  25. {
  26. emp obj;
  27. obj.display();
  28. getch();
  29. }

Summary

In this blog, I covered constructor, constructor types, and destructor in C++ language. If you face any problem, please comment. Thanks for reading.