What is definition of reference type?

Question

How do you define (explain) in a formal and strict way what is reference type in C++?

I tried to google, and looked into Stroustrup\'s \"The C++ Programming Language

Answer 1

A major difference between C and C++ (other than Objects and Classes!) is references. A reference is like a const pointer to a variable. Assigning a reference is a bit like using a pointer but with & not * and you don't need to difference. The difference is that you assign an address to a pointer but a variable to a reference variable. The line below suggests that the value of a is copied into aref. But it is not, instead aref is a reference to the variable a. Once assigned, aref is the same as a. Any changes to aref are changes to a as example below shows

int & aref = a;

 #include 
 #include "stdafx.h"

  int main()
   {
      int a=9;
      int & aref = a;
      a++;
      cout << "The value of a is %i\n" << aref;
      return 0;
    }

Also remember that

1. A reference must always refer to something.NULLs are not allowed.

2. A reference must be initialized when it is created. An unassigned reference can not exist.

3. Once initialized, it cannot be changed to another variable.

If it help you please inform me, thanx