References

1. A simple program demonstrating references

    Code Listing: 

// Purpose: A simple program demonstrating the use of reference

#include <iostream>
using namespace std;

int main()
{
int Len, Wid; // declare int variables

// Create references to int variables.
// Now rLen and Len are aliases to each other,
// and rWid and Wid are also aliases to each other.
int &rLen = Len;
int &rWid = Wid;

// Initialized the two int variables
Len = 10; // rLen is also initialized to be 10
Wid = 20; // rWid is also initialized to be 20

// Printing out the values for int and int references
cout << "Len is: " << Len << ", and Wid is: " << Wid << endl;
cout << "rLen is: " << rLen << ", and rWid is: " << rWid << endl;
cout << endl;

// Printing out the address of int and references to int
cout << "Address of Len is: " << &Len << endl;
cout << "Address of rLen is: " << &rLen << endl;
if(&Len == &rLen)
{
cout << "Address of Len is equal to address of rLen!" << endl;
}
cout << "Address of Wid is: " << &Wid << endl;
cout << "Address of rWid is: " << &rWid << endl;
if(&Wid == &Wid)
{
cout << "Address of Wid is equal to address of rWid!" << endl;
}

return 0;
}

    Running session:

Len is: 10, and Wid is: 20
rLen is: 10, and rWid is: 20

Address of Len is: 2147429924
Address of rLen is: 2147429924
Address of Len is equal to address of rLen!
Address of Wid is: 2147429932
Address of rWid is: 2147429932
Address of Wid is equal to address of rWid!
 

2. Function: passing by references

Code listing:

// Purpose: Demonstrates pass by reference in a function

#include <iostream>
using namespace std;

void swap(int &i, int &j); // function prototype for swapping two values

int main()
{
int NumOne = 0;
int NumTwo = 0;

cout << "Please enter two integers: " << endl;

cout << "Enter value for NumOne: " ;
cin >> NumOne;

cout << "Enter value for NumTwo: " ;
cin >> NumTwo;

cout << "Before swapping, NumOne is: " << NumOne << endl;
cout << "Before swapping, NumTwo is: " << NumTwo<< endl;

swap(NumOne, NumTwo);

cout << "After swapping, NumOne is: " << NumOne << endl;
cout << "After swapping, NumTwo is: " << NumTwo<< endl;

return 0;
}

// function definition for swap()

void swap(int &i, int &j)
{
int temp;

temp = i;
i = j;
j = temp;

}

Running session:

Please enter two integers:
Enter value for NumOne: 10
Enter value for NumTwo: 20
Before swapping, NumOne is: 10
Before swapping, NumTwo is: 20
After swapping, NumOne is: 20
After swapping, NumTwo is: 10