C++ Programming Concepts

Lecture 1

Introduction

Module Introduction – Text

• Deitel, H.M. & Deitel, P.J. (2003) C++ How to program, Prentice Hall, U.S. ISBN 0-13-111881-1

• Liberty, J. & Horvath, D.B. (2005) Teach Yourself C++ in 24 Hours, Sams, USA. ISBN 0-672-32681-7

• Overland, B. (2005)C++ Without FearPrenctice Hall, USA. ISBN 0-321-24695-0

Module Introduction - Text

• If available – second hand?Graham, N (1991) Learning C++McGraw Hill, USA. ISBN 0-07-100849-7

• Eckle, B. (2000) Thinking in C++ (Volume 1)Eckle, B. (2003) Thinking in C++ (Volume 2)– Both available as free download

http://www.mindview.net/Books/TICPP/ThinkingInCPP2e.html

– Vol 1 – 867KB; Vol 2 – 991KB

Some ‘C’ Revision

• Variable declarationsint nCount, iLoopCounter;

double dValue;

float fAmount;

long lBigValue;

int *ptrMyInt;

“C” – Hello World

#include <stdio.h>

void main(void)

{

printf(“Hello World.\n”);

}

“C” – Hello World

#include <stdio.h>

void main(void)

{

printf(“Hello World.\n”);

}

Pre-processor command

StandardInput / Output

Library

Control Character

Function Call

Function DeclarationType

String literal

“C” – Hello World : Functions#include <stdio.h>

void fnSayHello(void);

void main(void)

{

fnSayHello();

}

void fnSayHello(void)

{

printf(“Hello World. \n”);

}

“C” – Hello World : Functions#include <stdio.h>

void fnSayHello(void);

int main(void)

{

fnSayHello();

return 0;

}

void fnSayHello(void)

{

printf(“Hello World. \n”);

}

FunctionCall

Function Prototype

Function Declaration

Comments - C/* Pre-processor instructions */

#include <stdio.h>

int main(void)

{

/* Print output to screen */

printf(“Hello World!/n”);

return 0; /* Signal to system */

} /*end of main*/

Comments – C++// Pre-processor instructions

#include <stdio.h>

int main(void)

{

// Print output to screen

printf(“Hello World!/n”);

return 0; // Signal to system

} // end of main

Comments generally

• Possible to use either style within C++ code

• So…..

• …. make sure you use plenty!

• Together with– good variable names

and– good function / method names

Naming

• Hungarian Notation– Microsoft Web Site

• Simplified– Chuck Sphar– Cut down version

Simplified Hungarian

• Prefix name with lower case to indicate type.

char ‘c’ e.g. char cLetter;

integer ‘i’ or ‘n’ e.g. int nCount, iValue;

float ‘f’ e.g. float fLength;

double ‘d’ e.g. double dSalary;

pointer ‘p’ or ‘ptr’ e.g. char *pName, *ptrNext;

array ‘ar’ e.g. char arCustName[50];

etc….

Objects and Classes

• What is an Object?

• What is a Class?

• Some examples …..

Building Plans

House

Houses

Doing a “Delia”

IngredientsButter 110grms Sugar 110grmsEggs 2NoFlour 110gmsVanilla 3drops

MethodMix the ingredients together and bake.

Cake & Cakes

Objects and Classes

• Classes – the “instructions”

• Objects – what is created– Use Plans to build House(s)– Use Recipe to bake Cake(s)

• Live in house, eat cake

Use a class to create object(s)Use a class to create object(s)Use a class to instantiate object(s)

Classes → Objects

• Remember …..

• As with house plans and cake recipe

• Use class to instantiate one or more objects

• Interact with the objects

• Not the class

Attributes

IngredientsButter 110grms Sugar 110grmsEggs 2NoFlour 110gmsVanilla Ess. 3drops

MethodMix the ingredients together and bake.

Vanilla Sponge Cake

IngredientsButter 110grms Sugar 110grmsEggs 2NoFlour 110gmsOrange Ess. 3drops

MethodMix the ingredients together and bake.

Orange Sponge Cake

Attributes

IngredientsButter 110grms Sugar 110grmsEggs 2NoFlour 110gmsFlavouring 3drops

MethodMix the ingredients together and bake.

Generic Cake

Define flavour at time of

instantiation

Inheritance

• So far – a plain sponge cake with flavouring.

• ? Iced cake• ? Cake with crushed nuts topping• Rewrite the recipe• No …

– Take the basic recipe and add on the topping part.

Inheritance

Sponge Cake

Nutted

Take “Sponge Cake”Add Nuts

Iced

Take “Sponge Cake”Add Icing

Implementation Hiding

• Interact with objects via “methods”

• Consider a watch– Q – How interact with a watch?

• Example on next slide …..

A typical watch

Methods ?

Encapsulation

• Dictionary definition.– Encapsulate

“to express or show the most important facts about something”

Cambridge University Press Dictionary

http://dictionary.cambridge.org/

Code exercises – “Hello World”

// BrokenHello.cpp// This code is taken from "How not to programme in C++"// ISBN 1886411956

#include <iostream.h>

int main(void){

cout << "Hello World!/n";return (0);

}

Code exercises – classic error

// SimpleAccounting.cpp// This code is taken from "How not to program in C++"// ISBN 1886411956

#include <iostream.h>

int main(void){

// Amount owed (if any) by the userint amount;

cout << "Enter current balance: ";cin >> amount;

if(amount = 0)cout << "You owe nothing\n";

elsecout << "You owe " << amount << "\n";

return (0);}

Summary

• Overview of module– Concepts of OO – classes, objects etc.– Two pieces of code to try – and repair!