Chapter 5

CHAPTER 5
PROGRAMMING
1.0 BASIC PROGRAMMING CONCEPTS

1.1 Definition of program and programming language
 A computer program is a series of step by step
instructions telling the computer what to do.
 A programming language is a set of words (reserved
words such as Dim, If, Then, For, Next) symbols (=,*,&) and
codes (set of rules) that enables humans to communicate
with computers.
 Programming languages are used to write computer
program or develop software.
Examples of programming languages are COBOL, Java,
Javascript, HTML, Visual Basic 6.0, Ada, C, C++, C#, Pascal,
Ruby, Perl, BASIC,Prolog and Smalltalk.

1.2 Levels and generation of programming laguages

LOW LEVEL PROGRAMMING LANGUAGES

Low-level programming languages designed for a particular
complete and reflecting its internal machine code; low-
level languages are therefore often described as machine-
oriented languages that closer to the hardware.

Low-level programming language
Generation Explanation Examples
First Machine language is a set of
Generation instructions and data that a
computer’s central processing unit
can execute directly. Machine
Language
Machine languages instructions use a
series of binary digits (1s and 0s) or a
combination of numbers and letters
that represent binary digits.

Low-level programming language
Second Assembly language is the human-readable
Generation notation for the machine language used
to control specific computer operations.
Assembly
An assembly language programmer writes Language
instructions using symbolic instruction
codes that are meaningful abbreviations
or mnemonics.

With this language, a programmer write
abbreviations such as ADD for addition,
CMP for compare, MUL for multiply.

An assembler is a program that translates
assembly language into machine
language.

1.2 Levels and generation of programming laguages

HIGH LEVEL PROGRAMMING LANGUAGES

High-level programming languages allow the specification
of a problem solution in terms closer to those used by
human beings. These languages were designed to make
programming far easier, less error-prone and to remove the
programmer from having to know the details of the
internal structure of a particular computer. These high-level
languages were much closer to human language.

High-level programming language
Third The third generation of programming
Generation language 3GL or procedural language uses
a series of English-like words that are
closer to human language to write BASIC
instructions. LOGO
SmallTalk
High-level programming languages make
complex programming simpler and easier C
to read, write and maintain. C++
Pascal
Program written in a high level Java
programming language must be translated
into machine language by a compiler or
interpreter.


Fourth The fourth generation programming
Generation language or non-procedural language,
often abbreviated as 4GL, enables users to
access data in a database. SQL can be SQL
used to query data. NOMAD
FOCUS
A very high-level programming language is Intellect
usually limited to a very specific
application that might use syntax which is
never used in other programming
languages.


Fifth The fifth generation programming
Generation language or visual programming language
is also known as natural language.
Prolog
Provides a visual or graphical interface, Mercury
called a visual programming environment,
for creating source codes.

Fifth generation programming language
allows people to interact with without
needing any specialize knowledge.

1.3 PROGRAMMING LANGUAGE APPROACHES
PROGRAMMING LANGUAGE APPROACHES

Object-Oriented Approach Structured Approach

(a) Object-Oriented approach is a computer programming
techniques based on the concept of an “object” that
combine both data and the function into a single unit.
Programming approaches may includes features such as
encapsulation, polymorphism and inheritance.
Examples of OOP : C++, Java, Visual Basic 2005, C#
(a) Structured approach is computer programming
technique in which the program is divided into modules
like function, subroutine and procedure.
Examples: Pascal, C

DIFFERENCES BETWEEN OOP AND STRUCTURED APPROACH
STRUCTURED Differences OBJECT-ORIENTED
APPROACH APPROACH
Structured Uses Object-Oriented approach
programming uses object
approached uses a top
down design model
The programmer Emphasize The programmer packages
divides programming the data and the function
problem into module into a single unit, an object
like function
Medium programming Suitable for Large programming language
language

1.4 TRANSLATION METHOD OF PROGRAMMING USING
ASSEMBLER, INTERPRETER & COMPILER

TRANSLATOR

Assembler Interpreter Compiler

(a) An Assembler is a computer program that translates
assembly language into machine language.
(b) An Interpreter is a computer program that translates a
high-level language into machine language. Interpreter
translates programming statement of a program into
machine language; no object code is saved and then
executes it immediately, line by line. (Interpreted code
generally run more slowly)
(c) A Compiler is a computer program that translates a
high-level language into machine language. Compiler
translates entire programming statement of a program
into machine language, save it in an object code file
and then executes it later.

DIFFERENCES BETWEEN INTERPRETER AND COMPILER
INTERPRETER Differences COMPILER
Translate programming Translate entire
statement line by line Method programming statement and
and execute it execute it later.
immediately
No object code is saved Object code Store machine language as
object code on the disk
Interpreted code run Running time Compiled code run faster
slower

Study Case: Microsoft Visual Basic

Visual Basic programming language uses both an
interpreter and a compiler. The programmer can use the
interpreter during program development. When the
program is complete and error free, the programmer can
compile the program so it runs faster when it is placed into
production for users to execute.

1.5 BASIC ELEMENTS IN PROGRAMMING
(A) CONSTANT
(B) VARIABLE
CONSTANT differences VARIABLES
Constant retain their Characteristics Variables can change
value during program their value during
execution program execution
const PI = 3.142 examples Dim Name as String
Const GRAVITY = 9.8 Dim Score as Integer
Const WAGE = 5.5 Dim Mark as Integer

1.6 DATA TYPES
(a) Boolean (b) Integer (c) Double
(d) String (e) Date
Data type determines the type of data a variable can store,
for example a number or a character.
DATA TYPES EXPLANATION
Integer Integer data type contains any whole number
(Number) value that does not have any frictional part
Examples: Age, Mark and Temperature.
17, 85 and -5
Double Double data type contains any decimal number
(Number) value that has a fractional part.
Examples: Wages, Fees and Weight
RM 3500.45, RM 33.00, 33.3 kg

DATA TYPES EXPLANATION
String String data type contains a sequence of
(Text) character.
Examples: Name, Address and IC Number.
Ahmad, Jalan 2 Taman Permata, 850306-02-
5264
Boolean Boolean data type contains either a true or
(Logical Value) false value.
Examples: Paid (school fee), Result, Passed and
Married (Marital Status)
If Not Paid then msgbox(“Please pay
immediately)
If Passed then msgbox(“Good”)
Date Date data type contains date and time value.
Examples: DOB, Date of payment, Time
7/8/91, 2-Sept-2007, 12:24 AM

1.7 MATHEMATICAL AND LOGICAL OPERATORS

Operator is a symbol or notation that tells a computer to
perform certain actions or operation.

MATHEMATICAL MEANING
OPERATOR LOGICAL MEANING
OPERATOR
+ Plus
And And Operator
- Minus
Or Or Operator
* Multiply
Not Not Operator
/ Divide

Comparison Operator or Relational Operator

COMPARISON MEANING
OPERATOR
> Greater Than
< Less Than
= Equal
<> Not
<= Less Than or Equal

DIFFERENCES BETWEEN MATHEMATICAL
AND LOGICAL OPERATOR

Mathematical Differences Logical
Mathematical Logical operators are
operators are notations notations that tell the
that tell the computer computer to perform
to perform Function logical operations such
mathematical check the status of two
operations such as Boolean values
addition, subtraction,
multiplication and
division
+, -, *, / Symbol And, Or, Not

1.8 SEQUENCE CONTROL STRUCTURE AND SELECTION
CONTROL STRUCTURE
SEQUENCE CONTROL SELECTION CONTROL
STRUCTURE STRUCTURE
A sequence control structure A selection control structure will
executes statement one by execute statements based on
one in linear order certain conditions
Programmer uses sequence Programmer uses selection
control structure when control structure when he/she
he/she want to execute code want to implement decision
line by line making process in the program
The program does not use The program has to use the
the decision symbol decision symbol

STRUCTURE STRUCTURE

False
Action 1 Condition

Action 2
True
Action 3 Action 2 Action 1

Sequence Control Structure Selection Control Structure

STRUCTURE STRUCTURE
Example 1: Example 1:
Dim marks as integer If marks > 50 then
Input “Please enter marks”; Print “Passed”
mark else
Example 2: Print “Failed”
Dim no1 as integer End If
Dim no2 as integer Example 2:
no = 4 If answer = no1 + no2 Then
no = 6 Print “Excellent”
Print “Addition” Else
Print “Number 1”; no1 Print “Please, Try Again”
Print “Number 2”; no2 End if
Input “Your answer”;
answer

1.9 FLOW CHART

SYMBOLS NAMES EXPLANATION
Terminal Use to show the
Begin or End beginning or end of a
program
Flowline Use to connect symbols
and indicate the
sequences of operation
Input or output Use to show either an
(Print/Display) input operation(e.g an
input from the user) or an
output operation (e.g
print or display messages)

1.9 FLOW CHART

SYMBOLS NAMES EXPLANATION
Process Use to show a process to
(Formula) be carried out (e.g.
calculation)
Decision Use to shows a decision
(If-Then-Else) (or choice) to be made.
The program should
continue along one of two
routes (e.g. if…then…else)

1.9 FLOW CHART
Draw a flow chart to show how a program calculates the
area of a circle. Begin

Get length,
base, width

Volume of a cuboid =
length*base*width

Print volume
of a cuboid

End

Draw a flow chart to make a decision. If student has more
than 50 marks then he will pass. Begin

Get mark

False
Mark > 50

True

Print “Failed” Print “Pass”

End

1.10 PSEUDO CODES
•Pseudo codes is text only sentences that describe the logic
and program flow of a computer program.
•Pseudo code assembles plain English.
•It usually does not have any specific programming language
syntax and grammar.
•Pseudo code is directly linked to the computer codes
because each pseudo code statement can often be
converted into the programming language virtually line by
line.
•There are no set of rules for writing pseudo code.
•A programmer can have his or her personalized pseudo
code.
•He or she must use consistent language and syntax in the
pseudo code, so that he or she can understand it at a later
stage.

Write a pseudo code to show how a program calculates the
area of a circle.

Pseudo Code
Begin
Get radius
Calculate area of a circle = ½ * PI * radius 2
Print area of circle
End

Draw a flow chart to make a decision. If student has more
than 50 marks then he will pass.

Pseudo Code
Begin
Get marks
If mark > 50 Then
Print “Passed”
Else
Print “Failed”
End If
End

2.0 PROGRAMME DEVELOPMENT PHASES

5 MAIN PHASES IN PROGRAM DEVELOPMENT

• Problem Analysis

•Program Design

•Coding

•Testing & Debugging

•Documentation

PROBLEM ANALYSIS

1. Identify input, processing, output and data
component
2. Refer to book and website
3. Ask expert
4. Meet with system analyst and users

PROGRAM DESIGN

1. Divide all program activities into program
modules
2. Create solution algorithm for each program
modules (logic structure)
3. Describe the flow or steps of a program with
English statement. (pseudo code)
4. Create a pictorial diagram of the logical
sequence of a program (flowchart)
5. Design/Draw user interface

CODING

1. Coding a program involves translating the
solution algorithm into programming
language usually on paper.
2. Typing the code into the computer using
programming language such as Pascal, C++
and Visual Basic.

TESTING AND DEBUGGING

Several methods have been devised for finding
and removing logic error and syntax error.
1. Manually testing with sample data
2. The program is run through a computer,
using a translator program. Before the
program will run, it must be free of syntax
errors. Such errors will be identified by the
translator.
3. Testing by a select group of potential users.
Potential users try out the program and
provide feedback.

DOCUMENTATION

Documentation is important for people who may involve
with the program in the future.

Programmers: As time passes, even the creator of the
original program may not remember much about it. Other
programmers wishing to update and modify it (program
maintenance)

DOCUMENTATION

Activity:
1. Produce a description of the program, layouts of the
input and output records and a program listing.
2. Produce a problem definition, flow chart and pseudo
code.
3. Write comments with the program code(internal
documentation). These comments explain the
program’s purpose of the code statements within the
program.
4. Write a document for a novice users that explains how
to use or operate the program (write a user guide).

Chapter 5

More Related Content

What's hot

Viewers also liked

Similar to Chapter 5

Recently uploaded

Chapter 5