Wavelet transform And Its Applications to Image Processing

1
Writing a Good Program 5. Objects and Classes
in C
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
5.3 Modular Programming with C
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Doing Business by Selling Classes

• The development of Object Oriented Programming
  has enabled a new business in software
  development.
• ? People develop different classes and sell to
  other people.
• These classes often provide functions that are
  popularly used in applications.
• ? For example, the Java calculator used in some
  Web pages
• People post the advertisement of their classes on
  the Web. Those who are interested in their
  classes can directly download it and perhaps pay
  by credit card.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C

• Assume that you have designed the following class
  CAT and would like to sell it to a customer.

include ltiostreamgt // for cout using namespace
std class Cat // declare the class
object public void SetAge (int age) int
GetAge() void SetWeight (int weight) int
GetWeight() private int itsAge int
itsWeight

• You do not want to give him the source codes of
  the member functions since your customer may copy
  your codes.
• They may modify it and re-sell it to somebody
  else.

int CatGetAge() return itsAge void
CatSetAge(int age) itsAge age
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C

• If the customer has the source code, he may try
  to modify it by himself.
• It may introduce a lot of hidden errors as he
  knows very little about your program .
• The resulting program can be very difficult to
  debug.

Conclusion It is better to give your customer
executable codes such that they cannot read or
modify it.
Problem 1 A program without main() cannot be
built. No executable codes can be generated
without main(). Problem 2 If your customer only
has the executable codes, how can he know the way
to use your class?
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Static Library

• Rather than giving your customer the executable
  codes, you can give him a (static) library.
• Inside a library, it does not contain the
  executable codes, but the object codes machine
  code waiting for linking.
• Since object codes cannot be read directly, your
  customer cannot modify your codes.
• To enable your customer to know how to use your
  class, give also your customer a header file that
  contains the definition of your class.

Header
library
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Explain why public and private
CatClass.h
main() of the Customer
class CAT
Show that the class CAT has a public function
called GetAge() It will return an integer.
Main Program


MainProject.cpp

include "CatClass.h"
public int GetAge()

void main()




CAT Frisky Age Frisky.GetAge()

Library

Contain the implementation of GetAge(), however,
the source code cannot be seen by the customer.
10 20 2d 35 5f 43 23
43 23

When the customer builds the main(), it links
with CatClass.h and the library.
22 6f
21 44 dd 23
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Modular Program Design

• Besides doing business with classes, the use of
  static library also facilitates modular program
  design.
• The system analyst analyses the requirement of a
  program and divides it into a number of modules.
• The specifications of each module, such as its
  functions, the calling methods, the parameters
  returned, are well defined.
• Based on the specifications, the development of
  each module will be done by different programmers.

Very useful for team work
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Example step 1 obtain the requirements

• The system analyst talks with the customer and
  obtains the following program requirements

• A program is to be designed to show a zoo that
  contains different kind of animals, including
  dog, cat, sheep, and horse.
• At the beginning of the program, all animals are
  drawn on the screen.
• When user clicks on an animal, the sound of it is
  played.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Example step 2 design the program flow
Start

• Based on the requirements, the system analyst
  designs the program flow using, for example, a
  flow chart.

Draw animal
All animal drawn?
No
Yes
B
User click on animal?
No
Yes
A
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Click Dog?
Yes
A
B
Play dog sound
No
Click Cat?
Yes
Play cat sound
No
Click Sheep?
Yes
Play sheep sound
No
Click Horse?
Yes
Play horse sound
No
Click End?
Yes
End
No
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Example step 3 divide into modules

• From the flow chart, identify the classes
  required and their functions.

CatClass.h
HorseClass.h
DogClass.h
class CAT

class HORSE

SheepClass.h
class DOG




public int DrawShape() int
PlaySound()


class SHEEP
public int DrawShape() int
PlaySound()



public int DrawShape() int
PlaySound()


public int DrawShape() int
PlaySound()







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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Example step 4 ask programmers to
develop the modules

• For each module, the system analyst will ask a
  programmer to develop the codes required (to
  implement the class).
• To speed up the process, the system analyst may
  ask 4 programmers to develop the modules
  simultaneously.
• The codes developed by the 4 programmers may be
  different.
• If the specifications are correct, all modules
  are correct irrespective to the differences in
  the codes.
• Hence facilitate team work.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Example step 5 integrate the modules
Integrating all modules by the system analyst
CatClass.h
Main Program
MainProject.cpp
class CAT
include DogClass.h"


include CatClass.h"

void main()

public int DrawShape() int
PlaySound()


DOG Bobby CAT Frisky Bobby.DrawShape() Fris
ky.DrawShape()

Library for DOG


10 20 2d 35 5f 43 23
Frisky.PlaySound()
43 23



22 6f
Skeleton
21 44 dd 23
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Computer Programming and Basic Software
Engineering
Interface versus Implementation
5. Objects and Classes in C

• The declaration of a class stored in the header
  file is in fact a contract between the System
  Analyst and Programmer, and between the developer
  and customer.
• System Analyst who wants to use the object of
  this class should follow the rules given in the
  declaration.
• Class should be implemented exactly the same way
  it is declared otherwise the customer using it
  will have errors.
• C is strongly typed, i.e., the compiler will
  enforce the contracts and set the error flag if
  someone violates them.
• In the language of OO programming, this contract
  is named as interface.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Create a Static Library with Visual C

• Suppose you are one of the programmers and is
  asked to develop the class CAT.
• Now, the system analyst sets out two
  specifications for the class CAT
• It should have a function that allows the setting
  of CATs age. The function is
• void SetAge(int age)
• It should have another function that allows the
  reading of CATs age. The function is
• int GetAge()

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Step 1 Create the class required
class CAT // declare the class public void
SetAge (int age) int GetAge() private int
itsAge

• Based on the specifications, you may design the
  above class CAT.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Step 2 Implement the class
class CAT // declare the class public void
SetAge (int age) int GetAge() private int
itsAge int CATGetAge() return
itsAge void CATSetAge(int age) itsAge
age
To be put to header file

• For each member function, develop the required
  codes for building the library
• Keep this restricted

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Step 3 Test the class

• Create the header file and a main() for testing
  the functionality of the class.
• This main() is only for testing purpose, not
  supposed to be used in real application.

MainTest.cpp
include ltiostreamgt using namespace std include
"CatClass.h" // --- put implementation here int
main() CAT Frisky Frisky.SetAge(7) int Age
Frisky.GetAge() cout ltlt Age ltlt endl return
0
CatClass.h
class CAT public void SetAge (int age)
int GetAge() private int itsAge
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Step 4 Create the library with Visual C

• Assume your class is fully tested. You can create
  your library using Visual C.
• Start your Visual C .NET.
• In Visual C .NET, start a new project as usual.
• Set the location to store your library project
  to, e.g. e\temp\ENG236\Ch5
• Set the project name, e.g. LibCat
• However, when choosing the Application type in
  the Application Settings window, choose Static
  library and uncheck the option Precompiled header.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C

• In Visual C .NET Solution Explorer, under
  Header Files, right-click Add ? New Item ... and
  choose Header File (.h)
• Set the Header File name to, e.g. CatClass
• Click Add and the header file CatClass.h will be
  added to the project LibCat.
• Type in the class declaration.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C

• Type your class declaration here
• Remember to comment your codes

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C

• In Visual C, click Project/Add New Item... and
  choose C File (.cpp)
• Set the C source file name, e.g. CatCodes
• Click OK and the C source file CatCodes.cpp
  will be added to the project LibCat
• You may verify it by checking the Solution
  Explorer.
• Type the codes for the implementation of the
  member functions.
• Remember to include your header file and be
  careful of its location.
• Build the library by clicking Build Solution.

Give LibCat.lib
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C

• You need to enter the correct path of the header
  file
• It shows that the CatClass.h is in the current
  folder of CatCodes.cpp

Solution Explorer window

• After building the library, result is shown.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Step 5 Send the library and header file to the
System Analyst.

• Locate the files CatClass.h and LibCat.lib and
  send to the System Analyst.
• CatClass.h shows the class definition.
• From its content, the System Analyst knows how to
  use the class.
• LibCat.lib contains the codes for the
  implementation of the member functions.
• It is in object code form such that even the
  System Analyst cannot interpret or modify the
  codes.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
e\temp\ENG236\Ch5\LibCat\ debug
e\temp\ENG236\Ch5\LibCat\LibCat
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Computer Programming and Basic Software
Engineering
Step 6 Integrating into the application
5. Objects and Classes in C

• Open a Win32 Console project, e.g. MainProject in
  the folder e.g. e\temp\ENG236\Ch5\ .
• Enter the codes for the main() and other
  functions if necessary to implement the
  application.
• Copy CatClass.h and LibCat.lib sent from the
  programmer to current folder e\temp\ENG236\Ch5\Ma
  inProject\MainProject
• In Visual C, click Project/Add Existing Item...
  under MainProject. Select All Files to show all
  the files in the folder.
• Add CatClass.h and LibCat.lib to the project.
• Build Solution and run the application.

Prog.cpp
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
After building the application, the result is
shown
See the added CatClass.h and LibCat.lib here
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
You may double-click LibCat.lib. You can only see
some hex codes. No source codes can be found
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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
To see how to use the class CAT, double-click
CatClass.h
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Computer Programming and Basic Software
Engineering
Exercise 5.3 - Requirements
5. Objects and Classes in C

• Write a program using Visual C to do the
  following
• A class CAT must be created and your program will
  repeatedly ask user to choose one of the
  following
• Set the weight of a cat
• Get the weight of a cat
• Ask the cat to Meow!
• Quit
• If the user chooses (a), the user will be asked
  to input the weight of the cat and the program
  will store it up.
• If the user chooses (b), the weight of the cat
  will be shown on the screen.
• If the user chooses (c), show the following
  message on the screen Meow, Meow ... Meow.
• If the user chooses (d), quit the program.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Exercise 5.3 (cont.) - Activity

1. Two students in a group. One plays the role of a
   System Analyst. One plays the role of a
   Programmer.
2. The System Analyst should design the program
   structure using flow chart and define the
   specifications of the class required.
3. The Programmer should develop the class and build
   a library (with the header file required). You
   may email your library file and header file to
   the System Analyst.
4. After receiving the files from the Programmer,
   the System Analyst should integrate them into the
   application .
5. Show the result to your tutor.

34
Computer Programming and Basic Software
Engineering
Exercise 5.3b - Requirements
Not marked
5. Objects and Classes in C

• Write a program using Visual C to do the
  following
• A class PHONE must be created and your program
  will repeatedly ask user to choose one of the
  following
• Set the serial no. of a phone
• Get the serial no. of a phone
• Ask the phone to ring!
• Quit
• If the user chooses (a), the user will be asked
  to input a 6-digit serial no. of the phone and
  the program will store it up.
• If the user chooses (b), the 6-digit serial no.
  of the phone will be shown on the screen.
• If user chooses (c), show the following message
  on the screen Ring ... Ring, Ring ... Ring
• If user chooses (d), quit the program.

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Computer Programming and Basic Software
Engineering
5. Objects and Classes in C
Exercise 5.3b (cont) - Activity

1. For the same group, interchange the role of group
   members. The Programmer will play the role of
   System Analyst now and the System Analyst will
   play the role of Programmer now.
2. The System Analyst should design the program
   structure using flow chart and define the
   specifications of the class required.
3. The Programmer should develop the class and build
   a library (with the header file required). You
   may email your library file and header file to
   the System Analyst.
4. After receiving the files from the Programmer,
   the System Analyst should integrate them into the
   application .
5. Show the result to your tutor.

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Acknowledgment

• The slides are based on the set developed by Dr.
  Frank Leung (EIE).