Constructor in Object Oriented Programming

Constructor in Object Oriented Programming

Q. 1 What is the ambiguity between default constructor and default argument constructor in Object Oriented programming? 

In an C++ program, the default argument constructor can be called with either one argument or with no arguments. when called with no arguments, it becomes a default constructor. When both these forms are used in a single class, then it cause ambiguity for a statement such as A a; The ambiguity is whether to call A :: A() or A :: A(int i=0) 

Q. 2 Define copy constructor in Object Oriented programming?  

In an C++ program, a copy constructor is used to declare and initialize an object from another object in a single class. It takes a reference to an object of the same class as an argument. 

For example: A obj2(obj1);  this statement would define the object obj2 at the same time and initialize it to the values of obj1. 

Another form of this statement is A obj2 = obj1; The process of initializing through a copy constructor is known as copy initialization . 

Q. 3 Define multiple constructors (constructor overloading) in Object Oriented programming?  . 

In an C++ program, when a class that has different types of constructor then that class is known as multiple constructors class. 

Let us explain the working of multiple constructor in a class with the help of an example:

Program Code: 

#include<iostream> 

using namespace std;

class A 

{ 

int a;

int b; 

public: 

A( ) //default constructor of class A

{ 

a = 0;

b = 0;

cout<<" Value of a and b after initialization through default constructor of class A :";

cout<<a<<" "<<b;

cout<<endl;

} 

A(int x, int y) //parameterized constructor of class A

{ 

a = x; 

b = y; 

cout<<" Value of a and b after initialization through parameterized constructor of class A :";

cout<<a<<" "<<b;

cout<<endl;

} 

};

int main() 

{ 

A obj1; //invokes default constructor of class A 

A obj2(5, 6); //invokes parameterized constructor of class A

return 0; 

} 

The program output is tested on www.jdoodle.com

Output:

Value of a and b after initialization through default constructor of class A : 0 0

Value of a and b after initialization through parameterized constructor of class A : 5 6

Thanks

Mukesh Rajput