introduction to problem solving c++

CHAPTER 1 INTRODUCTION TO PROBLEM SOLVING

MOHD RIDZUAN B ABDUL RAHMAN

BACHELOR IN COMPUTER FORENSIC

MANAGEMENT & SCIENCE UNIVERSITY

Objectives

Introducing programming concept

Introducing technique to develop a program

TCS1013 INTRODUCTION TO PROGRAMMING CHAPTER 1

1.1 Definition of Program, Programming and Programmer

To understand program design in application software, user should know definitions of:

Program:

A set of step-by-step instructions that directs a computer to perform a specific

task and to produce the required results.

Programming:

Programming is a process of designing or creating a program.

Programmer:

Programmer is a person who writes the program.

1.1.1 Steps of Program Execution

Input – Refer to the process of entering data, program and instructions into the

computer system using input devices.

Process – Computer processed raw data into usable information to be used by

user. The process is done by the CPU (Central Processing Unit ).

Output – Output is raw data that has been processed by the computer (result).

Output will be converted to understandable form before displayed or printed.

MOHD RIDZUAN B ABDUL RAHMAN 1

INPUT (data) OUTPUT (information)

PROCESS (processor)


Example: Flow of ATM program

Assume that our transaction is money withdrawal. The instructions are:

a. Get card number from user (Input)

b. Get pin number from user (Input)

c. Process the input data (Process)

d. Get the transaction chosen by user (Input)

e. Get the account type from user (Input)

f. Process the transaction (Process)

g. Withdraw amount of money required by user (Output)

h. Print Receipt for user (Output)

Input: Example: Card number, pin number, type of transaction, type of account,

amount of money to withdraw.

Process: Example: Process to identify card number, valid pin number, type of

transaction, type of account and deducts the withdrawal from user account.

Output: Example: Receipt will show balance in user account and money withdrawal.

1.1.2 Executing A Program

To execute a program, CPU will examine each program instruction in memory and send

out the required command signals to carry out the instruction.

During execution, data can be entered into memory and manipulated in some specified

way (delete and modify) as required.

Program instructions are used to copy a program's data (data input) into memory.

After the input data are processed, instructions for displaying or printing are executed.

Result displayed by a program is called “program output”.


INPUT PROCESS OUTPUT


Example: Money withdrawal from ATM machine.

First step:

Data entered by user and stored in memory (input).

Second step:

CPU will instruct program to process the card number and ATM pin number with the

data in memory at the same time. Program will execute the transaction choose by

user and store the result in memory.

Third step:

The outputs are money and receipt (output).

1.2 Programming Process (Programming Life Cycle)

Cycle: Refers to the needs for changes of old program to new program (the cycle will

start again).

Programming Life Cycle: A framework or discipline, which using the techniques needed

in computer programming development.


Machine language program for processing card number and PIN number.

Data entered during execution.

Computed results.

Central Processing

Unit.

Output results:Receipt and money

Input data: Card Number, PIN Number, and transaction.

Program Output

Step 1

Step 2

Step 3


Steps that involved programming life cycle:

STEP 1: PROBLEM ANALYSIS

Purpose:

To describe in details a solution to a problem by providing the needed information for the

problem.

How?

First, understand & study the problem.

Identify:

o The input to the problem.

o The required output.

o The relevant process. For example, scientific formula or appropriate theories if any.

Problem 1: Write a program that get 3 numbers as input from user. Find the average

and display the numbers and the average.

Problem Analysis:

Input: 3 numbers.

Process: 1. Add the numbers

2. Divide the total with 3

Output: The 3 numbers and average


PROGRAM DESIGNPROGRAM DESIGN

PROGRAM CODINGPROGRAM CODING

TESTING AND DEBUGGINGTESTING AND DEBUGGING

MAINTENANCEMAINTENANCE

DOCUMENTATION

PROBLEM ANALYSISPROBLEM ANALYSIS

Documentation: Process of recording the steps carried out during the development.

Each step must be completed before moving to next step.

Documentation: Process of recording the steps carried out during the development.

Each step must be completed before moving to next step.


STEP 2: PROGRAM DESIGN

Definition: It defines the framework or the flow or the problem solution

Method to design a program:

1. Algorithm

Algorithm is a sequence of instructions to solve a problem written in human

language and problem can be solved if follow the correct procedure

A programmer writes the solution in the form of an algorithm before coding it into

computer language.

Example of algorithm to calculate the average of 3 numbers:

1. Set Total=0, average=0;

2. Input 3 numbers

3. Total up the 3 numbers

Total= total of 3 numbers

4. Calculate average

average=Total/3

5. Display 3 numbers and the average

2. Flowchart

A graphical representation of data, information and process or an orderly step-by-step

solution to a problem.

Example:


INPUT PROCESS OUTPUT


3. Pseudocode

Steps in problem solving written in certain of programming code and certain in human

language.

For example, some part use C++ language code and some part use English-like

phrases.

Example:

STEPS 3: PROGRAM CODING

Definition: Write a solution into a specific programming language such as C, C++, COBOL

and etc.

Solution: Instructions before it is coded into programming language.

Purpose:

To produce a program to develop a system.


START

INPUT a, b, c

Total = a + b + c

average = Total / 3

OUTPUT a, b, c

OUTPUT average

END

# include <iostream.h>

main( ){

int a, b, c, HasilTambah; double purata;

cout<<" Enter 3 numbers:"; cin>>a >> b >> c; HasilTambah = a + b + c; purata = HasilTambah / 3; cout<< a = “<<a <<”\n”; cout<<b = “<<b<<endl; cout<<”\nc = “<<c; cout<<"Average is = “<<purata;

return 0; }

Example of syntax in C+

+ language to display

instruction for user to

enter 3 numbers on

computer screen.


Example of programming in C++ language:

STEP 4: TESTING AND DEBUGGING

Definition of Testing:

Using a set of data to discover errors and to ensure accuracy of the program.

Testing Process:

Diagram indicates the process of testing.

Example 1:

Assume that a program to find the average of 3 numbers has been coded. Then, execute the

program with a few sample data (value) in order to verify whether the program is functioning well

and produce the accurate output (result).

Testing 1:

Input :4,5,8


Input three numbers:

4 4 4

Average of the numbers: 4.00_

Input: Three numbers entered by user.

Output: The average of 3 numbers

Output Screen:

#include<iostream.h>#include<conio.h>

main( ){

int a,b,c; // input variables int sum; // variable - holds the result of (a + b + c) float avg; // output variable clrscr( );

// Ask user to enter 3 numbers cout<<"\n Input three numbers : "; cin>>a >> b >> c;sum = a + b + c; // calculate the addition of a, b, c avg = sum / 3; // calculate the average of a, b, c

// display the average of the 3 numbers cout<<"\n Average of the numbers : "<<avg;

return 0;

}

Input sample of data set Executing Program

Output (functioning well or error discovered


Testing 2:

Input :7,8,6

Definition of Debugging:

An error is called as bug.

Bug must be identified and corrected; the process is called debugging.

Two types of error:

1. Syntax Error (grammatical error)

Occurs when the rules of programming language are not applied.

It is usually found and corrected during coding a program.

Can be traced by the compiler during compilation.

Also known as compile-time error

Must be corrected before executing and testing the program.

2. Logic error

Cannot be traced by compiler.

Always found and corrected during problem solving.

Also known as run time error.

Example: The correct output is 4 but when it runs the output is 2.


From the output, is the program produce the correct output?

Line 9 where the syntax error occurred.

Syntax error message

- Syntax error will

occur if any mistake

in the program.

- Example:

No semicolon.


STEP 5: MAINTENANCE

Definition:

Activity to verify that the operational system is still performing as planned or modified to

enhance the system to meet the current requirement.

The process of changing a system after it has been applied is to maintain its ability. The

changes may involve simple changes such as correct errors, coding and enhancement.

How to do maintenance?

By performing activities such as:

o Testing – test the ability of the system.

o Measurement – access data time. Example, time to save, print and others.

o Replacement – replace the old system to new system.

o Adjustments – adding needs to new system.

o Repairs – Example, old system cannot update new data,


SYNTAX ERROR

#include<iostream.h>#include <conio.h>

main(){

int a, b, c;int sum;

float avg;clrscr();

cout<<“Input three numbers: “ ;cin>>a >> b >> c;sum = a + b + c; avg = sum/6;cout<<“Average of the three numbers: “<<avg;

}

Logic ErrorLogic Error

Input three numbers:4 4 4Average of the numbers: 2

The wrong outputThe wrong output

LOGIC ERROR

Logic error is an error that occurred

because of incorrect of logical statement

in program.

Example:

Sum is total of the 3 numbers.

Supposed the average is sum / 3

because there are 3 numbers.

Logic error is an error that occurred

because of incorrect of logical statement

in program.

Example:

Sum is total of the 3 numbers.

Supposed the average is sum / 3

because there are 3 numbers.


o Updating – modify database.

Example: Maintenance of Telecommunication System TELEKOM.

o Telecommunication System TELEKOM provides

communication service from one house to another house. The telephone number is

7 digits.

o Assume that management wants to change 7 digits to 8

digits.

o Programmer will change the old system to new system and

test the system whether it functioning well or not.

o Then, new system will be tested its capability overall. For

example, test the capability to identify caller’s and user’s location and time is taken to

connect them (measurement).

o Any old function that no longer used will be replaced with

new function (replacement).

STEP 6: DOCUMENTATION

Definition:

Documentation is a written report or graphic record of the steps carried out

during the development of program.

Purpose: It is useful in the future if the program needs modification/maintenance. It is

a reference for the development team.

Content of Documentation:

o Description of the program.

o Specification requirement of program

o Program design such as pseudocode and flowchart

o List of program and comments (to explain about the program).

o Test results.

o End user manual.

o Program capabilities and limitation.

Example: Problem solving using the steps in Programming Life Cycle

Problem: To calculate total payment for fee in Murni Tuition Centre. Provided

packages:

Package 1 (RM 55): Bahasa Melayu, Bahasa Inggeris, Sejarah

Package 2 (RM 50): Matematik, Sains, Geografi

Package 3 (RM 50): Bahasa Melayu, Matematik, Sejarah



Package 4 (RM 55): Bahasa Inggeris, Sains, Geografi

Package 5 (RM 50): Bahasa Melayu, Sains, Geografi

Package 6 (RM 55): Bahasa Inggeris, Matematik, Sejarah

STEP1: Problem Analysis

Input: Subjects taken according to package

Process: Calculate fees based on the package

Output: Monthly fees to pay

STEP 2: Algorithm

1. Set payment:

Package_1: RM 55

Package_2: RM 50

Package_3: RM 50

Package_4: RM 55

Package_5: RM 50

Package_6: RM 55

2. Set Fee = 0

3. Enter name and package

4. If Package = 1

Fee = Fee + Package_1

Else

If Package = 2


Else

If Package = 3


Else

If Package = 4


Else

If Package = 5


Else

If Package = 6


Else

“Invalid data



5. Display name and fee

Flowchart

PseudocodeSTART

Package_1= RM 55Package_2= RM 50Package_3= RM 50Package_4= RM 55Package_5= RM 50 Package_6= RM 55Fee = 0Input name, Package If Package = 1

Fee = Fee + Package_1Else

If Package = 2Fee = Fee + Package_2



ElseIf Package = 3



ElseIf Package = 5



Else“Invalid Data”

OUPUT name, FeeEND

STEP 3: Program Coding (C Language)

#include <iostream.h>

main (){

float Package_1= 55, Package_2= 50, Package_3= 50, Package_4= 55;float Package_5= 50 , Package_6= 55, Fee = 0;

cout<<“Enter student name:<<”\n”;cin>> nama;

do{cout<<“Enter Package:” <<”\n”;cin >>Package;if (Package == 1)

Fee = Fee + Package_1;else

if (Package == 2)Fee = Fee + Package_2;

elseif (Package == 3)


if (Package == 4)Fee = Fee + Package_4;

elseif (Package == 5)


if (Package == 6)Fee = Fee +

Package_6;else

cout<<“Invalid data”; cout<<“Do you want to continue?”; cin>>terus;

} while (terus == ‘Y’);cout<<“Name: ”<<nama;cout<<“Monthly fee to pay:”<<Fee;

}



STEP 4: Testing and Debugging

No error has detected. Program runs efficiently after testing.

Output as required.

STEP 5: Maintenance

Maintenance to enable the program to process number of students in one time.

o Programmer will modify current system to new system and

test the system whether it’s functioning or not.

o Then, new system will be tested overall. For example, test

the capability to process student’s data in one time and the duration to process the

data (measurement).

o Any old function that no longer used will be replaced with

new function (replacement).


introduction to problem solving c++

Documents

programming

pin number

card number

abdul rahman

mohd ridzuan

tcs1013 introduction

steps carried

data entered