Answer to Question #325930 in C++ for Prasoon Giri

Question

Explain the type of constrcuors with the examples.

Answer 1

#include<iostream>

using namespace std;

/*A constructor is a special type of member function of a class which initializes
objects of a class. In C++, Constructor is automatically called when object
(instance of class) is created. It is special member function of the class
because it does not have any return type*/

//Types of Constructors

//1. Default Constructors : Default constructor is the constructor which 
//doesn’t take any argument.It has no parameters.


class Person
{
	int age;
public:
	Person():age(18){}
	void Display() { cout << age << endl; }
};
/*2. Parameterized Constructors: It is possible to pass arguments to constructors.
Typically, these arguments help initialize an object when it is created.
To create a parameterized constructor, simply add parameters to it the way
you would to any other function. When you define the constructor’s body,
use the parameters to initialize the object.*/
class Person2
{
	int age;
public:
	Person2(int _age) :age(_age) {}
	void Display() { cout << age << endl; }
};
//3. Copy Constructor: A copy constructor is a member function which
//initializes an object using another object of the same class.
class Person3
{
	int age;
public:
	Person3(int _age) :age(_age) {}
	Person3(Person3& p) :age(p.age) {}
	void Display() { cout << age << endl; }
};




int main()
{
	//1 - Default constructor
	Person a;
	a.Display();
	//2 - Parametrized constructor
	Person2 b(30);
	b.Display();
	//3 - Copy constructor
	Person3 c(25);
	Person3 d(c);
	c.Display();
}