Constructor, Types Of Constructor And Destructor In C++

This blog talks about constrcutors, types of constructors, and destrcutors in C++.

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

• Default Constructor
• Parameterized Constructor
• Copy Constructor

Before creating a constructor, always remember the below points.

• Constructor name is same as the class name.
• It is declared with no return types (int, float, double and not even void).
• It is declared in the public section.
• It is invoked automatically when the objects are created.

Default Constructor

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

Example

// default constructor example
#include<iostream.h>
#include<conio.h>
class emp
{
    int id,sal; //member variable
    public:
        emp() //default constructor
        {
            id=1;
            sal=2000;
        }
        void display() // member function for display data
        {
            cout<<"Employee id: "<<id<<endl;
            cout<<"Employee salary: "<<sal<<endl;
        }
};
void main()
{
    emp obj;
    obj.display();
    getch();
}

Parameterized Constructor

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

Example

//parameterized constructor

#include<iostream.h>
#include<conio.h>
class emp
{
    int id,sal; //member variable
      public:
        emp(int empId,int empSal) //parameterized constructor
        {
            id=empId;
            sal=empSal;
        }
        void display() //member function
        {
            cout<<"Employee id: "<<id<<endl;
            cout<<"Employee salary: "<<sal<<endl;
        }
};
void main()
{
    emp obj(1,3000); //passing constructor argument value
    obj.display();
    getch();
}

Copy Constructor

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

Example

//copy constructor

#include<iostream.h>
#include<conio.h>
class emp
{
    int id,sal;
    public:
        emp(int empId,int empSal) //paramereized constructor
        {
            id=empId;
            sal=empSal;
        }
        emp(emp &em)    //copy constructor
        {
            id=em.id;
            sal=em.sal;
        }
        void display() //member function
        {
            cout<<"\nEmployee id: "<<id<<endl;
            cout<<"Employee salary: "<<sal<<endl;
        }
};

void main()
{
    emp obj(1,2000);
    emp obj1(obj);

    obj.display();
    obj1.display();
    getch();
}

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.

• Destructor name is same as the class name and is prefixed with tilde (~).
• It can neither return a value nor can it take any parameter.

Example

// destructor example

#include<iostream.h>
#include<conio.h>
class emp
{
    int id,sal;
    public:
        emp()  //default constructor
        {
            id=1;
            sal=5000;
        }
        ~emp()    //destructor
        {
            cout<<"Ok Bye for now...";
        }
        void display() //member function
        {
            cout<<"Employee id: "<<id<<endl;
            cout<<"Employee salary: "<<sal<<endl;
        }
};
void main()
{
    emp obj;
    obj.display();
    getch();
}

Summary

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