1.16. Reference Variables

1.16. Reference Variables
	Chapter 1. C++ Introduction

[ fromfile: references.xml id: references ]

In essence, an lvalue is anything with a memory address that can be given a name.

In C++, a reference provides a mechanism for assigning an alternative name to an lvalue.
A reference must be initialized when it is declared.
The initializer of a reference must be an lvalue.

For example:

  int n;
  int& rn = n;

The ampersand & following the int indicates that rn is an int reference.

For its entire life, a reference variable will be an alias for the actual lvalue that initialized it.
This association cannot be revoked or transferred.

For example:

 int a = 10, b = 20;
 int& ra = a;         // ra is an alias for a
 ra = b;              // this causes a to be assigned the value 20

 const int c = 45;    // c is a constant: its value is read-only.
 const int& rc = c;   // legal but probably not very useful.
 rc = 10;             // compiler error - const data may not be changed.

The address-of operator applies to an object and returns its address. Hence, it appears only on the right side of an assignment or in an initializing expression for a pointer variable.
In connection with references, the ampersand is used only in the declaration of a reference. Hence, it appears only between the type name and the reference name as it is declared.

	Note
For reference declarations, we recommend placing the ampersand immediately to the right of the type name: Type& ref(initLval);

Note

For reference declarations, we recommend placing the ampersand immediately to the right of the type name:

 Type& ref(initLval);


1.15.3. Exercises: Pointers and Memory Access		1.17. `const` and `const`