Question

what is the usage of constructors and destructors in c++?

Answer 1

Constructors and destructors are fundamental to the concept of classes in C++. Both constructor and destructor are more or less like normal functions (but with some differences) that are provided to enhance the capabilities of a class.

Constructor, as the name suggests is used to allocate memory (if required) and construct the objects of a class while destructor is used to do the required clean-up when a class object is destroyed. In this article, we will study the concept of constructors and destructors through working examples.

If you are new to C++, you should first understand the concept of C++ classes.

Constructors and Destructors

Let’s understand the concept of constructors and destructors through this example :

#include<iostream>

class country
{
public:

country()
{
std::cout<<"\n Constructor called \n";
}

void setNumOfCities(int num);
int getNumOfCities(void);

~country()
{
std::cout<<"\n Destructor called \n";
}

private:

int num_of_cities;

};

void country::setNumOfCities(int num)
{
num_of_cities = num;
}

int country::getNumOfCities(void)
{
return num_of_cities;
}

int main(void)
{
country obj;
int num = 5;

obj.setNumOfCities(num);
num = obj.getNumOfCities();

std::cout<<"\n Number of cities is equal to "<<num;

return 0;
}