C++ Constructor

In C++, constructor is a special method which is invoked automatically at the time of object creation. It is used to initialize the data members of new object generally. The constructor in C++ has the same name as class or structure.

There are two types of constructors in C++.

Default constructor
Parameterized constructor

Default Constructor

A constructor which has no argument is known as default constructor. It is invoked at the time of creating object.

Example

Let's see the simple example of C++ default Constructor.

snippet

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

Output

Default Constructor Invoked Default Constructor Invoked

Parameterized Constructor

A constructor which has parameters is called parameterized constructor. It is used to provide different values to distinct objects.

Example

Let's see the simple example of C++ Parameterized Constructor.

Output

#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, "John", 890000); //creating an object of Employee Employee e2=Employee(102, "Nakul", 59000); e1.display(); e2.display(); return 0; }

Output

101 John 890000 102 Nakul 59000