Chap3

Muhamad Rizal Bin Mohamed RazaliProgramming Concept / ISD

Introduction

Course Work BreakdownQuiz =5%Midterm =15%()Assignment=15%()Lab=15%Final =50%

Learning GoalsAt the end of this module student will be

able:Read the C programDesign pseudocode and flow chatWrite C program using selection , looping

pointer and function command.

Outcome 3 Introduction & ObjectiveBefore we start writing a programming it is

essential to have a thorough understanding of the problem and carefully planned approach to solve the problem.

We can use Pseudocode Flow chartmethod how to solve the problem

Outcome 3Algorithm is a sequence of steps or

procedure to solve the problem.Example:-

Let say you have a friend to enroll as a student at your collage. Can u tell your friend how he/she can enroll as a student at your collouge.

Manual process for enrollment1. Go to the receptionists counter 2. Ask registration form3. Fill all the particulars4. Submit the form

Online process for enrollment1. Login to the collage website2. Click at the registration form3. Fill up the form4. Click submit button

Cont…Can you give me example algorithm how to

cook Nasi goreng ?

Cont..You have several algorithm to achieve the

same goal Every algorithm has a different cost and

time to accomplish.

PseudocodeAn outline of a program written in

English or the user's natural language; it is used to plan the program, and also serves as a source for test engineers doing software maintenance, it cannot be compiled.

You can write pseudocode without even knowing what programming language you will use for final implementation

Why needs pseudocode?1. Designing algorithms2. Communicating algorithm to users3. Implementing algorithms as programs4. Debugging logic error in programs 5. Documenting programs for future

maintenance and expansion purpose

How to write pseudocode1. Have a limited vocabulary2. Be easy to learn3. Produce simple instruction or simple

English like narrative notation4. Be capable of describing all algorithm ,

regardless of their complexity

Pseudocode Meaning

Read name Read a value from input device and store it under the specified name

Write name Write the value stored under the name to the output device

Write string Write whatever appears in the string

name = expression Evaluate the expression and store it under specified name

IF condition THEN statements In the condition is true then execute the statements otherwise ignore them

FOR counter = 1 TO n DO statements

Execute the statements ‘n’ times

REPEAT Statements UNTIL condition

Repeat the statements over and over until the condition is true

Case studyWrite a pseudcedo to show how to

withdraw money at ATM machine

Insert ATM cardKey in passwordChose withdraw menuChose type of accountEnter amountRemove ATM cardKeep the money

Flow ChartFlow chart is a schematic representation of

a processFlow chart is a graph consisting of

geometrical shapes that are connected by flow lines

In order to use flowcharts to communicate algorithms we must develop some convention for its symbols

Cont..

The basic flow chart symbols are as below:-

Descriptions Symbols

Start / End

Input / output

Processing / computational

Decision making /selection

Flow line

Cont…Draw a flow chart based on the

pseudocode below.display “enter your name”accept first _namedisplay “Enter your I/C number”accept ic_numberdisplay “enter your how many days you

works:”accept days _your _workcompute salary= 5.5 X days_your_work display first_name , days your work , “your

salary this month”,salary

Cont

Salary = 5.5 X how many days

Display first name I/C numbers & salary

Start

Enter first name

Read first name

Enter I/C number

Read how many days

Enter how many days

Read I/C number

End

Control StructureA control structure is a design that

determines the logic order of program instructions

Have 3 types of control structuresSequence control structureSelection control structureRepetition control structure

The sequence Control StructureIs a series of steps or statements that are

executed in order they are written in an algorithm

Selection control structureThe selection control structure defines two

courses of action depending on the outcome of a condition

The selection structure requires use of the keywords if and else.

Example…If password true

Chose withdraw menuChose account typeRemove ATM cardKeep the money

Else Reenter the password

Nested selection structureNested selection structure is a basic

selection structure that contains other if/else structure in it’s then part or else part

Useful for multi way decision making

Cont..If password true

If menu equal balance enquiry Chose account type

Else If menu equal withdrawChose account type

ElsePlease enter the correct menuEnd if

Else Reenter the password

End if

Repetition Control structureThe repetition structure permits a

sequence of instruction be executed repeatedly until a certain condition is reached

Cont..enter the password

While enter password not equal actual password

beginRepeat ask user to enter the passwordif user enter 3 times wrong password block the user

end

SummaryYou learn concept of problem solvingAlgorithm is sequence of a finite numbers

of step arrange in a specific logical order.Algorithm can described in term of three

basic control structure SequenceSelectionrepetition

QuestionsGet two numbers as input from the user

and display the sum of the two numbers to the screen.

Get a series of 5 integers and display the total

Read two numbers and compare which number is smaller and display the result

Read 3 numbers and print the largest number