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References and Pointers
Further C++ Object Oriented features example from a Well House Consultants training course
More on Further C++ Object Oriented features [link]

This example is described in the following article(s):
   • What are C++ references? Why use them? - [link]
   • Sigils - the characters on the start of variable names in Perl, Ruby and Fortran - [link]

Source code: refdemo.cpp Module: C234
#include <iostream.h>

/*

A pointer is a variable that holds the address of another
variable (object).

A reference is an alias to another variable (object)

*/


int main () {

        int weight = 96;
        int *pWeight = &weight;
        int &rWeight = weight;

        int another = 123;
        int athird = 770;

        cout << "weight " << weight << endl;
        cout << "pWeight " << pWeight << endl;
        cout << "*pWeight " << *pWeight << endl;
        cout << "rWeight " << rWeight << endl << endl;

// Note - following line does NOT reassign rWeight; it
// assigns a new value to the variable that rWeight references

        rWeight = another;

        cout << "weight " << weight << endl;
        cout << "pWeight " << pWeight << endl;
        cout << "*pWeight " << *pWeight << endl;
        cout << "rWeight " << rWeight << endl << endl;

// Following line changes pWeight only; it's NOT an alias
// so it leaves weight and rWeight alone

        pWeight = &athird;

        cout << "weight " << weight << endl;
        cout << "pWeight " << pWeight << endl;
        cout << "*pWeight " << *pWeight << endl;
        cout << "rWeight " << rWeight << endl << endl;

        return 0;
        }

/* Sample Output

munchkin:c234 grahamellis$ ./refdemo
weight 96
pWeight 0x7fff5fbffa2c
*pWeight 96
rWeight 96

weight 123
pWeight 0x7fff5fbffa2c
*pWeight 123
rWeight 123

weight 123
pWeight 0x7fff5fbffa24
*pWeight 770
rWeight 123

munchkin:c234 grahamellis$

*/

Learn about this subject
This module and example are covered on the following public courses:
 * Learning to program in C and C++
 * C++ for C Programmers
 * C and C++ Programming
 * Learning to program in C and C++
 * C and C++ Programming
Also available on on site courses for larger groups

Books covering this topic
Yes. We have over 700 books in our library. Books covering C and C++ are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples
This example comes from our "Further C++ Object Oriented features" training module. You'll find a description of the topic and some other closely related examples on the "Further C++ Object Oriented features" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

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This web site is written and maintained by Well House Consultants.

Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

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