Constructor and destructor in C ++

Shailendra Chauhan 7 min read

05 Sep 2023

Intermediate

1.16K Views

Introduction

Do you want to learn the basics of object-oriented programming in C++? Are you interested in understanding constructor and destructor functions, but don’t know where to begin? Don’t worry! Earning a C++ online course with certification will give you enough exposure to Constructors and destructors in C++ might be confusing for some, but we’re here to help! In this blog post, we will guide you through the essentials of constructing and deconstructing objects using these powerful tools. After reading this blog post, not only will you be an expert on constructors and destructors, but also acquire a deeper appreciation for why they are so crucial in object-oriented languages like C++. Let’s dive right into it!

What is Constructor in C++?

Constructor in C++ programming language is a special method that is invoked generally when an object is created. Constructor in C++ is a special type of function that is used to create objects. The constructor constructs (initializes) an object by assigning its initial values during the time of object creation. Constructors are called automatically when an object is created and do not require a return type just like other C++ functions. Constructors can also accept parameters for initializing class members or for any other purpose, based on user requirements. Constructors provide default initialization of objects if no arguments are provided to the constructor. Constructor helps to easily differentiate between the declaration and initialization in C++ programming language making it easier to program complex codes.

Different types of constructors in C++

There are two types of constructors in C++ programming language. Those are.

Default constructor in C++
Parameterized constructor in C++

What is default constructor in C++?

Default constructors in C++ programming language are extremely versatile and interesting tools for any programmer as well as for its user. Default constructors are automatically called when an object is created without being assigned a particular value. This particular process helps to simplify the development of complex classes and objects. Default constructors generally do not require any arguments, although parameters may be included if necessary. By using default constructors, any programmer can create accurate objects with minimal effort as they provide a solid foundation to build upon as more complicated logic is needed. Default constructors are therefore essential parts of C++ development and understanding them allows developers to craft efficient code quickly and accurately.

Example

#include <iostream> 
using namespace std; 
class Student 
 { 
   public: 
        Student() 
        { 
            cout<<"Default Constructor Invoked"<<endl; 
        } 
}; 
int main(void) 
{ 
    Student s1; //creating an object of Student 
    Student s2; 
    return 0; 
}

Output

Default Constructor Invoked 
Default Constructor Invoked

What is Parameterized Constructor in C++?

Parameterized Constructors in C++ programming language are a convenient feature for programmers as well as the user that allows them to assign values to object attributes when the object is created for the first time. By uniquely assigning values upon object creation, Parameterized Constructors help prevent errors and help optimize the writing process of the code of that particular program. Parameterized Constructors are also useful for assigning dynamic initialization values for each instance of an object since the parameters needed for initialization usually depend on the situation. They significantly reduce the amount of repetitive code that has to be written to initialize objects using C++ by allowing us to pass parameters from one constructor as arguments into another constructor. Parameterized Constructors come with some notable benefits such as improved organization of data and outputs and more efficient memory management, which make them an essential part of efficient C++ programming.

Example

#include <iostream> 
using namespace std; 
class Employee
{ 
   public: 
       int id;//data member (also instance variable) 
       string name;//data member(also instance variable) 
       float salary; 
       Employee(int i, string n, float s) 
        { 
            id = i; 
            name = n; 
            salary = s; 
        } 
       void display() {
            cout<<id<<" "<<name<<" "<<salary<<endl; 
    } 
} 
int main(void)
{ 
    Employee e1=Employee(101, "Urmi", 590000); //creating an object of Employee 
    Employee e2=Employee(102, "Bose", 29000); 
    e1.display(); 
    e2.display(); 
    return 0; 
}

Output

101 Urmi 590000
102 Bose 29000

What is Destructor in C++?

Destructor in C++ programming language is a special member function of a class that is used to clean up or deallocate the resources that are associated with an object of that particular class. Destructors are useful for freeing up allocated memory, closing files, and all other resources that were used in the instances of the class. Destructors are automatically called by C++ when an object is out of scope or deleted and are written as a method containing the same name as that of the class and a tilde sign preceding it which indicates destruction. Destructors cannot be inherited nor can they be overloaded and hence act differently compared to regular methods. Destructors are essential components of classes since they help ensure resources used by objects of that class get released when objects go out-of-scope so they can be recycled later.

Destructor in C++ with example

#include <iostream> 
using namespace std; 
class Employee 
 { 
   public: 
         Employee() 
        { 
            cout<<"Destructor Invoked"<<endl; 
        } 
}; 
int main(void) 
{ 
    Employee e1; //creating an object of Employee 
    Employee e2; //creating an object of Employee 
    return 0; 
}

Output

Destructor Invoked
Destructor Invoked

Summary

In this blog post, we discussed constructors and destructors in C ++. Constructors are responsible for initializing objects, while destructors are responsible for deallocating memory when an object is no longer needed. We saw what is a default constructor in C++ including both constructors and destructors, as well as how to use them together to create reliable code. If you still have trouble understanding these concepts, this article encourages you to enrol in a C++ Certification. With a little bit of effort, you'll be able to write code that takes advantage of the features of both constructors and destructors!