UNIT 2: PROBLEM ANALYSIS AND

DESIGN Algorithm, Flowchart, Pseudocode

and Analyse Problem

1. Defining and analyzing problems identify and understand what the problems to resolve are

the problems must be clearly define 3 element of problem analysis :- input, process, output

2. Planning of variables variables are simply references to memory locations a well plan use of variables will produce an efficient

execution of program in terms of speed and memory utilization

STAGE INVOLVED IN PROBLEM SOLVING

3. Design tools 3 types of design tools i) Flowchart ii) pseudo code

4. Program Writing the program should be clear and readable through an

orderly

4. Testing and Debug Once the program has been written it must be compiled and executed. This is accomplished by an editor and compiler. An editor lets us type a program, makes changes and save it to a file. The compiler then translates the program into a form that the computer can read. Once the program has been compiled and executed the presence of errors will be readily apparent.

5. Documentation Program must be documented for future references and maintenance process.

ELEMENTS OF PROBLEMS ANALYSIS

INPUT

A set of information called data that entered into the computer from keyboard, floppy disk, hard disk etc. and stored in a portion of the computer memory.

This input which is an input to the computer will then be processed to produce the desired result.

PROCESS

Sequence of interdependent and linked procedures which, at every stage, consume one or more resources to convert inputs into outputs.

These outputs then serve as inputs for the next stage until a known goal or end result is reached.

OUTPUT

The processed data which produced certain result is

known as the output.

The output data will be presented in a sheet of paper through the printer or display on a monitor.

LETS DO AN EXERCISES:

Determine input, process and output for the given

problems.

1. A workers at TF Supermarket will be paid RM5 per

hour. Get the total hours working per day and total days working in a month from the user and calculate the gross pay for a month.

2. Students have to get at least 50 marks to PASS Fundamental Programming Subject. Calculate the average marks for the students. Their marks consist of two quizzes, one test and one assignment.

3) Calculate the area of rectangular.

4) Calculate total parking fee that customer

has to pay at SOGO shopping complex.

Given rate for parking is RM2 per hour.

Input : Total hours working per day

Total days working in a month

Process : Gross pay = RM5 x hours a day x days in a month

Output : Gross pay

Input : Marks for

a) Quiz 1

b) Quiz 2

c) Test 1

d) Assignment 1

Process : Average = (Quiz1 + Quiz 2 + Test 1 + Assg 1)/4

Output : Average

1. DEFINE & ANALYZE PROBLEM

2. PLANNING VARIABLES

3.PROGRAM DESIGN TOOLS

4. PROGRAM WRITING

5. PROGRAM TESTING & DEBUGGING

6. DOCUMENTATION

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2 techniques

The Techniques To Develop C++ Programming

1. Flowcharts

2. Pseudo Code

STEP 3: PROGRAM DESIGN TOOLS

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F L O W C H A R T

Graphic representation of algorithm is known as flowchart which consist of geometric

symbols.

These symbols are connected by line of arrows called flowlines which indicate the direction of

flow of processes or activities.

The shape of the symbol indicates the type of operation that is to occur.

Flowchart should flow from the top of the page to the bottom.

Symbol

Name

Meaning

Flowline

Used to connect symbols and

indicate the flow of logic

Terminal

Used to represent the

beginning (start) or the end

(End) of a task

Input/output

Used for input and output

operations, such as reading

and printing. The data to be

read or printed are describe

inside

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Symbol

Name

Meaning

Processing

Used for arithmetic and data-

manipulation operations. The instruction

are listed inside the symbol

Decision

Used for any logic or comparison

operations. Unlike the input/output and

processing symbols, which have one entry

and one exit flowline, the decision symbol

has one entry and

two exit paths. The path chosen depends

on whether the answer to a question is

yes or no

Connector

Used to join different flowline

Offpage

connector

Used to indicate that the flow chart

continues to a second page

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Symbol

Name

Meaning

Predefined Process

Used to represent a group of

statements that perform one

processing task.

Annotation

Used to provide additional

information about another

flowchart symbol

The main advantage of using a flowchart to plan a task is that it provides a pictorial representation of the task, which makes the logic easier to follow. We can clearly see each and every step and how it is connected to the next step. For example lets look at the discount sales program in the next page.

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EXAMPLE:

1. A workers at TF Supermarket will be paid RM5

per hour. Get the total hours working per day

and total days working in a month from the user

and calculate the gross pay for a month.

Input : ______________________________

Process : _____________________________

Output : _____________________________

How many hours did you work?

START

Display message How many hours

did you work?

Read Hours

Display message How much do you get paid

per hour?

Read Pay Rate

Multiply Hours by Pay Rate. Store

result in Gross Pay.

Display Gross Pay

END

Variable Contents: Hours: ? Pay Rate: ? Gross Pay: ?

Output Operation

Stepping Through the Flowchart

How many hours did you work?

40

START

Display message How many hours

did you work?

Read Hours

Display message How much do you get paid

per hour?

Read Pay Rate

Multiply Hours by Pay Rate. Store

result in Gross Pay.

Display Gross Pay

END

Variable Contents: Hours: 40 Pay Rate: ? Gross Pay: ?

Input Operation

(User types 40)

Stepping Through the Flowchart

How much do you get paid per hour?

START

Display message How many hours did

you work?

Read Hours

Display message How much do you get paid per hour?

Read Pay Rate

Multiply Hours by Pay Rate. Store

result in Gross Pay.

Display Gross Pay

END

Variable Contents: Hours: 40 Pay Rate: ? Gross Pay: ?

Output Operation

Stepping Through the Flowchart

How much do you get paid per hour? 20

START

Display message How many hours

did you work?

Read Hours

Display message How much do you get paid per hour?

Read Pay Rate

Multiply Hours by Pay Rate. Store result

in Gross Pay.

Display Gross Pay

END

Variable Contents: Hours: 40 Pay Rate: 20 Gross Pay: ?

Input Operation

(User types 20)

Stepping Through the Flowchart

How much do you get paid

per hour?

START

Display message How many hours

did you work?

Read Hours

Display message How much do you get paid per hour?

Read Pay Rate

Multiply Hours by Pay Rate. Store

result in Gross Pay.

Display Gross Pay

END

Variable Contents: Hours: 40 Pay Rate: 20 Gross Pay: 800

Process: The product of 40 times 20 is stored in Gross Pay

Stepping Through the Flowchart

Your gross pay is 800

START

Display message How many hours

did you work?

Read Hours

Display message How much do you get paid per hour?

Read Pay Rate

Multiply Hours by Pay Rate. Store

result in Gross Pay.

Display Gross Pay

END

Variable Contents: Hours: 40 Pay Rate: 20 Gross Pay: 800

Output Operation

Stepping Through the Flowchart

PSEUDO CODE i) an

abbreviated version of

actual computer code

ii) geometric symbols used in flowcharts are replaced by English-like statements that outline the process

iii) allows programmer to

focus on the steps required

to solve a problem rather than on how to use computer

language.

Program: 1- Enter hours work - input 2- Enter rate paid per hour input 3. Gross pay=hour * pay rate - process 4. Display gross pay - output

DEBUGGED PROGRAMME SOURCES

CODE

SYNTAX ERROR

The most common error a programmer makes. Usually a miss spelled word.

A program will not compile until all syntax errors are corrected.

For interpreted languages however syntax errors cannot be detected until runtime and it is not necessarily simple to differentiate a syntax error from a semantic error.

RUN-TIME ERROR Run-time errors are errors that occur while your

program runs.

These typically occur when your program attempts an operation that is impossible to carry out.

LOGICAL ERROR These errors solely depend on the logical thinking of the programmer and are easy to detect if we follow the line of execution and determine why the program takes that path of execution.

SUMMARY

Design tools for problem solving:

Flowchart

Pseudo code

Various types of errors:

Syntax error

Run-time error

Logical Error

Element of problems analysis:

Input

Process

output

LETS DO AN EXCERCISES

Analyze the problem given, state all the possible variables and

develop a flowchart and pseudo code for each problems.

1. Students have to get at least 50 marks to PASS Fundamental Programming Subject. Calculate the average marks for the students. Their marks consist of two quizzes, one test and one assignment. Design a flowchart and pseudo-code.

Step 1 : Input : _______________________

Process: _____________________

Output: _______________________

Step 2 : List all posibble variables

___________________________________________

Step 3: Flowcahrt and pseudo-code

2) Write a flowchart and pseudo code to a program that will calculate the area of

rectangular.

Step 1 : Input : _______________________

Process: _____________________

Output: _______________________

Step 2 : List all posibble variables

___________________________________________

Step 3: Flowcahrt and pseudo-code

3) Calculate total parking fee that customer has to

pay at SOGO shopping complex. Given rate for

parking is RM2 per hour. Design the flowchart and

pseudo code for these program.

Step 1 : Input : _______________________

Process: _____________________

Output: _______________________

Step 2 : List all posibble variables

___________________________________________

Step 3: Flowcahrt and pseudo-code