Question

In C++ what is the difference between pointer variable and reference variable? Please give an example.

Answer 1

The difference between pointer variable and reference variable are:-

	Pointer variable	Reference variable
1.)	Pointer variable stores address of the variable.	Reference variable refers to variable that already exists but with other name.
2.)	Pointer variables can assign null value.	Reference variable cannot assign null value.
3.)	Pointer variable can be referenced by pass by reference.	Reference variable can be referenced by pass by value.
4.)	Pointer variable may or may not initialized on declaration.	Reference variable must initialized on declaration.
5.)	Pointer variables are able to have their own address of the memory.	Reference variable is used to share the identical address of the memory that too with the initial variable.
6.)	Pointer variables are able to have their own size on the stack.	Reference variable are able to take same memory on the stack.
7.)	Syntax: type *pointer;	Syntax: type &newname =existing name;

Example :-

Reference variable in C++:

#include<iostream>
using namespace std;
int main()
{
int n = 40;
int& reference = n;
reference = 50;
cout << "n = " << n << endl ;
n = 60;
cout << "reference = " << reference << endl ;
return 0;
}

Output:

n = 50

reference = 60

Pointer variable in C++:

#include <iostream>
#include <string>
using namespace std;

int main() {
string animal = "Dog";
string* ptr = &animal;
cout << animal << endl;
cout << &animal << endl;
cout << ptr << endl;
return 0;
}

Output:

Dog                                                                                                                                             

0x7fff4a80d6e0                                                                                                                                  

0x7fff4a80d6e0