ENG2002 Computer Programming - Lnx01 @ DELL …lnx01.ee.polyu.edu.hk/~eewlchan/ENG2002/Ch1-2.pdf ·...

ENG2002 Computer Programming

Subject Lecturer: Dr. W.L. Chan

THE HONG KONG

POLYTECHNIC UNIVERSITY

Room: CF609E-Mail: [email protected]: 27666145lnx01.ee.polyu.edu.hk/~eewlchan/ENG2002

Subject coordinator: Dr Frank Leung (EIE)Email: [email protected]: CD633 Tel: 2766 6224

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References:

1. S. Rao, Sams Teach Yourself C++ in One Hour a Day. Indianapolis, Ind.: Sams, 2012.

2. P.J. Deitel and H.M. Deitel, C++ How To Program(9th ed.) Boston, Mass.: Prentice Hall, 2014.

3. J Liberty and R. Cadenhead, Sams Teach Yourself C++ in 24 hours (5th ed.) Indianapolis, Ind.: Sams, 2011.

Computer Programming

THE HONG KONG


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Teaching Plan:

1. Introduction to Programming (week 1)2. A Taste of C++ (week 1)3. Bolts and Nuts of C/C++ (week 2-4)4. Program Design and Debugging (week 5)5. Basic Object Oriented Programming (week 6-7) 6. Pointer and Array (week 8-11)7. Stream I/O (week 12)

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Student Learning Outcomes:

� Familiarize themselves with at least one C/C++ programming environment.

� Be proficient in using the basic constructs of C/C++, to develop a computer program.

� Be able to develop a structured and documented computer program.

� Understand the fundamentals of object-oriented programming and be able to apply it in computer program development.

� Be able to apply the computer programming techniques to solve practical engineering problems.

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Assessment Plan:

� One application development - 20% (a group of 2 students)

� Two programming tests - 30% (open book)

� Others - 20% (quizzes & assignments)� Exam - 30% (closed book )

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0 - 34 F

35-40 D

41-46 D+

47-53 C

54-60 C+_______________________61-70 B71-80 B+_______________________81-90 A91-100 A+


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Marks to grade mapping:

Schedule for the programming tests

� First programming test – week 8

� Second programming test – week 13


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Lectures� Monday, 9:30 – 11:20

� Thursday, 15:30 – 17:20

Tutorials and practices� Monday, 8:30 – 9:25

� Thursday, 17:30 –18:25


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Programming� Programming is very different from other

engineering subjects !� Just like learning a foreign language – you

need to speak more often, read more often� To learn programming well, you must write

your own program !!!� Think logically, plan and design properly before

you start writing your program !!!

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Computer Programming:

A systematic approach to instruct a computer doing something for us.

Computer Programming1. Introduction to Programming

Hardware

CPU

Memory

I/O devices

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Process of Computer Programming

Computing Problems

Algorithmsand Data

Structures

High-levelLanguage

Hardware

Operating System

Application Software

Coding

Binding(Compile, link and load)

Mapping


Details in the following slides

Way of thinkingComputer

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Computing Problems

Algorithmsand Data

Structures

High-levelLanguage

Hardware

Operating System


Coding


Mapping


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Identify the Problem• Before writing a program, ask yourselves two questions:

1. What is the problem I want to solve?

2. Do I really needto write a program to solve it?

• A problem can often be so large that requires the co-operation of a few programs to solve it

• E.g. To design a computer game

- Design the story

- Design the graphics

- Design the motion

:


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• Do we need to write a program for the following problems?• Calculate the result of 1 + 1?

• Play a piece of MP3 music using the computer?

• Develop a Web page?

No. Just use your fingers!

No. Use application software such as Media Player.

Yes or no, depending on how complicate your Web page is.

• Usually we need to write a program if the problem is too complicatedand specificto our needs.


Local computer Vs networked computers

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Computing Problems

Algorithmsand Data

Structures

High-levelLanguage

Hardware

Operating System


Coding


Mapping


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Find the Best Algorithm• A problem can be solved by different approaches

• Using a clever approach can save you a lot of time in getting the result

• E.g.Calculate 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 +

10 + 11 + 12• Solution?


11 additions

Use algorithm A: 12 x (1 + 12) / 2 = 781 addition, 1 multiplication, 1 division

Seems better, BUT ...

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• Consider the following situation:• For a particular computer, it may take 1 µs to

compute an addition but uses 10 µs to do a multiplication or division.

Calculate 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12

• Do you still want to use algorithm A?

Direct addition: 11 µsec Direct addition: 11 µsec Use algorithm A: 21 µsec Use algorithm A: 21 µsec

� Algorithm needs to match with the hardware architecture� Algorithm needs to match with the hardware architecture


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Computing Problems

Algorithmsand Data

Structures

High-levelLanguage

Hardware

Operating System


Coding


Mapping


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Coding• Computer can only understand 0 and 1

• The most direct way to communicate with the computer is to use 0 and 1

⇒ Machine Language Programming

0110001111000010

0001000111100011

:

:

0011000100001000

1000001001010101

MachineLanguageProgram

Very tedious and can make error easilyVery tedious and can make error easily

1. Introduction to Programming


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Coding - Assembly Language• Assembly Languageis created to help human instructing

CPU to work

• By using a software tool called Assembler, assembly language programs can be converted into machine language programs.

Assembler

01100011110000100001000111100011

::

00110001000010001000001001010101

LD R0, #05ADD R0, $1234

::

SUB R0, #22LD $2345, R0

Assembly Language Machine Language



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Coding - High Level Language

• Assembly language programmingis still too complicatedfor general users

• They are far from human used language

e.g. “Set W equal to W plus X minus Y divided by Z”

“Repeat the next sequence of instructions until X is less than 0 or Y equals Z”

• A high level languageis required to reduce the gapbetween human and computers.



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Give me the result of adding 1 to 10

Compiler

Linker10110101010101010101

:

High Level Program

ExecutableMachine Language Program

Object codeLibrary


.exe

.cpp

Details in the following slides

Start

Finish


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• Compiler: Generate the object code

• Object code � Similar to the machine language code but cannot be executed because of the missing of some information.

• Linker : Resolve the missing information from the library or other programs.

For a program, it is very common that some of the information in the program needs to be obtained from the Library provided by the programming tool. It is the job of linker to obtain these missing information.

For a program, it is very common that some of the information in the program needs to be obtained from the Library provided by the programming tool. It is the job of linker to obtain these missing information.



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Coding - High Level Languages• From time to time, high level languages (HLL)are designed

for different purposes

• Earlier examples:BASIC : for simple and general computing (obsolete for long) COBOL : for data processing (still using in local banks)FORTRAN : for scientific computation (ever replaced by C or C++)

• Recent examples:Pascal: a sophisticated but complicated HLL (replaced by C or C++)

C : a simple structural HLL for general computing (still in use)

• Current examples:C++ : the most well-knownobject-oriented (OO)language

Java : an OO language designed with the concept of networking.



� FORTRAN – FORmula TRANslator– 1954-1957: IBM– Complex mathematical computations

� Scientific and engineering applications

� COBOL– COmmon Business Oriented Language – 1959: computer manufacturers, government and

industrial computer users– Precise and efficient manipulation of large amounts

of data� Commercial applications



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What is C?� C is a general purpose, procedural, imperative

language developed in 1972 by Dennis Ritchie at Bell Labs for the Unix Operating System.– Low-level access to memory– Language constructs close to machine instructions– Used as a “machine-independent assembler”



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My First C Program

#include <stdio.h>/* My first C++ program! */int main(){

printf("hello, world\n");return 0;

} char array/string

Indicate correct termination

Write to standard output

A preprocessor directive

Include standard io declarations



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Programming Language C++• Object-Oriented programming concept is overwhelming

• OO Programming has the advantage of achieving reuse of software components

• The C++ programming language is created to implement the concept of OO programming

• C++ is an extension to the widely popular C language

• It has become the predominant language for the development of commercial software

• Standardized by the American National Standards Institute (ANSI), C++ program is portable to different machines.



“Hello World” in C++

using namespace std;#include <iostream>// My first C++ program!int main(){

cout << "hello world!" << endl;return 0;

}

Use the standard namespace Include standard iostream classes

A C++ comment

cout is an instance of ostream

operator overloading(two different argument types!)



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Java

� Eliminated unsafe features of C++� Concurrency features� Libraries for applets, GUIs, database access� Portable: Java Virtual Machine concept, JIT

compilers� Widely used for WWW pages� Use for other areas increased faster than any

other language (Android Apps)



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Hello World in Java

// My first Java program!public class HelloWorld {

public static void main(String[] args) {

System.out.println("hello world!");}

}



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Scripting Languages for the Web

� JavaScript– A joint venture of Netscape and Sun Microsystems– Used in Web programming (client side) to create dynamic

HTML documents– Related to Java only through similar syntax

� PHP– PHP: Hypertext Preprocessor– Used for Web applications (server side); produces HTML code

as output

� Python– An OO interpreted scripting language– Type checked but dynamically typed– Supports form processing



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Hello World in JavaScript

<html><body>

<script>// My first JavaScript program!// helloWorld.html

alert("Hello World");</script>

</body></html>



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Machine binary language Low-level assembly High-leve l



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Coding - High Level Languages

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Programming Environment

• Before doing any C++ programming, first we need to familiarize with the programming environment.

• A programming environment is a software packagethat can help us developand testprogram code.

• For PC, one of the most popular programming environment is Microsoft Visual Studio.

• It is more popular because of its direct support to the Microsoft Windows environment.

Computer Programming2. A Taste of C++

• Visual C++is one of the components of the product –Visual Studio, which also contains development tools for other programming languages, e.g. Visual Basic, Visual C#, etc.

• The version we use is Visual Studio Community 2015. The compiler that is incorporated is Visual C++ 2015.

• Additional features include

• Produce C++/CLI codesthat run in the Common Language Runtime (CLR)

• Allow the use of .NET Framework class libraries.

Visual Studio Community 2015

NOT

covered in

ENG2002

2. A Taste of C++


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Solution and Project• In Visual Studio, each user task is referred to as a

solution to a problem.

• A solution refers to the computer resource(such as memory, disk space, etc.) required for one or more projects to complete the task.

• Every project contains • executable codeand debuginformation• files containing the C++ programs• classesand objectsused in the project• other related resources such as

• icon images used in the project• graphical user interface (GUI), e.g. button, menu.

They are all in files


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Solution

Project 1

Project 2 Project 3

Files

• A Solutionmust contain at leastone Project

• A Projectmust contain at leastone File


Source ProgramEditing

Display compilation results

Display resources

of the solution, such as, projects and files inside

2. A Taste of C++


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Project Example

• Solution Explorerallows us to clearly see the different files includedin the project


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2. A Taste of C++

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Project Example

Program can be typed here

2. A Taste of C++

Built result (result of compiling and linking)

shown here


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Build your first project -HelloWorld• Building a project means to produce target

executable files (.exe files)based on the program codes.

• Project can be built to execute in consoleorwindows mode• Console mode:Use the Command Prompt for

input/output• Windows mode:Use the Windows environment

for program execution.


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Command Prompt• It is a traditional interface between the user

and computer• User types in commands to instruct computer

to work.


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Build your first project - HelloWorld

#include <iostream>

int main(){

std::cout << "Hello World!" << std::endl;return 0;

}

• Hello.cpp : File containing a C++ program that prints a message “Hello World!” on the console output.

The returned typeof main() MUST be declaredin Visual Studio 2015


� Inserts the contents of another file (Library) into the program

� Is a preprocessor directive– Not part of the C++ language– Not seen by compiler

� Example: for the cout object #include <iostream>

The #include Directive

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The cout Object� Displays information on computer screen� Use << to send information to cout

std::cout << "Hello World!";

� Can use << to send multiple items to cout std::cout << "Hello " << “World!";

Or std::cout << "Hello ";std::cout << “World!";

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Starting a New Line

To get multiple lines of output on screen - Use endl

std::cout << "Hello World!" << std::endl;

- Use \n in an output stringstd::cout << "Hello World!\n";

2-4848


Step 1:

Start Microsoft Visual Studio 2015

Click New Project...

First time starting may take minutes, be patient.

2. A Taste of C++


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2. A Taste of C++

Step 2 You can modify the location of the files of your project.

Note where you create this project


Step 3


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2. A Taste of C++

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2. A Taste of C++

Step 4:

Right-clickSource Files ,select Add→ New Item...


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2. A Taste of C++

Step 5:Choose C++ File (.cpp) .

Give a name to the C++ file you are going to add


a

Source ProgramEditing

Display compilation results

Solution Explorer

Display resources of the solution, such as, projects and files inside

2. A Taste of C++


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Step 6:

Type the program on p.37 in here

Click Build→ Build Solution

See the built result


Do you see the following result?

Note: The result is shown in the Command Prompt (cmd.exe) – Console Application

Step 7:

Execute the program by clicking Debug → Start Without Debugging


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2. A Taste of C++

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What has actually done?• In this HelloWorld

example, one solution is created that contains aproject called chap2p1 .

• Inside the project, there is one C++ program called Hello.cpp .

Solution

Project: chap2p1

C++ sourceFile: Hello.cpp


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• The C++ Compiler of Visual Studio compilesthe program Hello.cpp and generates an executable file chap2p1.exe.

• When you click Debug → Start Without Debugging , Visual Studio actually runs the executable file chap2p1.exe for you.

• All files generated in this project is stored in

E:\VS_Proj\chap2p1

Run Windows Explorer


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2. A Taste of C++

Contains all files created after building the solution

Contains info. about the project. Double-click this will automatically start the project

The C++ file you created

Computer ProgrammingWindows Explorer

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2. A Taste of C++

The EXE(executable) file created


Program Input Using the cin Object� cin Object: allows data entry to a running

program� Use of the cin object causes the program to

wait for input from the keyboard� When keyboard entry is complete, the program

resumes execution, using the entered data� An output statement preceding the cin object

statement provides a prompt to the user

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cin.get();

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2. A Taste of C++ We can always run the program under the command prompt

We can always run the program under the command prompt


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Exercise 2.1Consider the two programs on the RHS. For each of the program, construct a new project in Visual Studio and then build the solution.

For each program, note the error messages when building the project. Fix the errors and execute the resulting project. What do you see?

#include <iostream>int main()

cout << "Hi World!" << std::endl;

return 0;}

#include <iostream>int test(){

std::cout << "How are you!"<< std::endl;

return 0;}


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Exercise 2.21. Open the Command Prompt .2. By using the command cd , change the current folder to the

folder that contains chap2p1.exe (you may want to use the command dir to show the content of a folder.)

3. Run chap2p1.exe by typing its file name and press Enter .

4. Compare the result with that you run the program in Visual Studio. Can you see any difference coming up?

5. If no, add the following lines of code before “return 0 ;” of Hello.cpp .

std::cout<<"Press Enter to continue."<<std::endl;

std::cin.get();

Rebuild the solution. Repeat 1 to 4 and note any difference.

Observe the output and explain.


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