Reference Variables and Pointers

Comparing References and Pointers
• Reference variables are aliases for other variables. Pointers, however, are independent variables that contain the addresses of other variables
• Consequently, a reference variable has the same memory address as the variable it references. A pointer, on the other hand, has a different memory address than the variable it points to
• A pointer can be manipulated to point to different locations, a reference variable references a constant location
• Assigning a value to a reference variable is equivalent to assigning a value to a dereferenced pointer. For example:
  

  int x = 10, *ptr; // Initialize x and declare pointer ptr 
  int &ref = x; // Defines ref as a reference to x
  ptr = &x; // Assigns the address of x to ptr
  ref = 100; // Changes the value of x to 100
  *ptr = 200; // Changes the value of x to 200
  

• The following program demonstrates the differences between pointers and references:
  

  /******************************
   File: ref.C
  ******************************/
  #include <iostream.h>
  
  int main()
  {
  	int x = 55;
  	int &y = x; //CREATE REFERENCE VARIABLE y
  	cout << "x is an integer, y is a reference to x...\n";
  	cout << "&y = " << &y << "\n"; //PRINT ADDRESS OF y
  	cout << "y = " << y << "\n"; //PRINT CONTENTS OF y OR x
  	cout << "&x = " << &x << "\n";//PRINT ADDRESS OF x 
  	cout << "x = " << x << "\n";//PRINT CONTENTS OF x
  
  	int *b;//DECLARE AN INTEGER POINTER b
  	int a = 21;
  	b = &a;//ASSIGN THE ADDRESS OF a TO b
  	cout << "\na is an integer, b is a pointer to a...\n";
  	cout << "&b = " << &b << "\n";//PRINT THE ADDRESS OF b
  	cout << "b = " << b << "\n";//PRINT THE CONTENTS b
  	cout << "*b = " << *b << "\n";//PRINT THE CONTENTS OF a
  	cout << "a = " << a << "\n";//PRINT THE CONTENTS OF a
  	cout << "&a = " << &a << "\n";//PRINT THE ADDRESS OF a
  
  	exit(0);
  }
   
  Output:
   
  x is an integer, y is a reference to x...
  &y = 0xdffffd9c
  y = 55
  &x = 0xdffffd9c
  x = 55
  
  a is an integer, b is a pointer to a...
  &b = 0xdffffd94
  b = 0xdffffd90
  *b = 21
  a = 21
  &a = 0xdffffd90