informational technology

1. Introduction to Software
Development and Programming
Language
Made By
Prashant Kumar
Amit Dahiya
Siddhant Mohanpuria
Pankaj Gautam

2. 2
Content
 Software
 What is Software?
 Types of Software
 Why develop new Software?
 Introduction to Software Development
 Process Models
 The Waterfall Model
 Programming Language
 System Software
 Languages

3. 3
Software
 Why is it so important?
 The economies of ALL developed nations are
dependent on software.
 9/11 highlights this with the destruction of the stock
exchange computers
 More and more of our daily lives are being
supported/monitored by software
 The engines of our cars
 Our washing machines
 Getting on a bus/train

4. Operating System
{ Application The Computer
4
What is Software?
 Software is the part of a
computer that makes it
useful.
 In this module we are going to
focus upon application software
development.
 Software is not tangible.
 It is ‘conceptual’ so doesn’t wear
out like hardware.
 Software is a set of
instructions (Programs).
 These are acted upon (executed)
by the hardware.
 Software is also the documents
that describe the operation and use
of the programs.
Hardware
Software
• Windows 98/2000/XP
• Linux/Unix
• Browser
• Email
• Word Processor

5. 5
What does it do?
Application
Operating System
Hardware
 Generally software takes in data and processes it
into information.
 The many different types of software basically vary
from where/whom data is acquired and where/whom
information is sent/given.
Data In Processing Information
Out
From the
user/device
/sub-system
To the
user/device
/sub-system

6. 6
Types of Software
 Generic (Off-the-shelf) Applications
Application
Operating System
Hardware
 Well known packages such as word processors,
accounting, image editing, … to name but a few.
 Anyone is able to buy them.
 Bespoke (Customized) Products
 Systems that are built specifically for individual
people/organisations.
 They can also be generic software packages that are
customized.
 The high-cost nature of this type of software
means it is not economically available to all.

7. 7
Types of Software
 System Software
Application
Operating System
 This type of software exists at the Operating
System layer. It is the operating system itself,
compilers, editors….any kind of software that
supports the execution and/or development of
applications.
 Application Software
 Real-time Software
 Programs that monitor/analyse/control real world events.
A nuclear power plant cooling system is a good
example.
Hardware

8. 8
Types of Software
 Application Software
 Business Software
Application
Operating System
Hardware
 Business Information Systems such as payroll, accounts
and order management/tracking. There are off-the-shelf
packages available for small businesses, however large
businesses usually develop their own software.
 Engineering and Scientific Software
 Typically ‘number crunching’ programs for areas such as
astronomy, molecular biology, weather forecasting and
Computer Aided Design (CAD) for engineers. Generic
programs do exist for some of these areas, however
research usually requires new software to be developed.

9. 9
Types of Software
 Application Software
 Embedded Software
Application
Operating System
Hardware
 Intelligent products such as cookers, washing machines
and microwaves use embedded software that typically
resides in a Read Only Memory (ROM). Due to the
individual nature of such products this software is
usually developed/tailored for each.
 Personal Computer Software
 Spreadsheets, word processors, computer graphics,
multimedia and database applications are typical. This
type of software is predominantly off the shelf but does
go through many versions to remove bugs and increase
functionality.

10. 10
Types of Software
 Application Software
 Artificial Intelligence (AI) Software
Application
Operating System
Hardware
 AI is used to solve complex problems such as
scheduling the maintenance of manufacturing equipment
to minimise their shutdown. Other uses include pattern
recognition (speech/visual). This software is typically
newly developed for each application.
 The application of computers through
software development is only limited by our
imaginations……(and its’ cost)

11. 11
Why develop new Software?
 As hardware will always eventually wear out, it will
need to replaced.
 Software on the other hand, doesn’t wear out in this
traditional sense, but will become increasingly less
useful as users requirements for it changes over
time.
 This means that software needs to be either periodically
updated or replaced.
 Understanding the process of software development
is therefore paramount in keeping software
systems/applications continually useful to its users.

12. Introduction to the Software
Development Process
 There are many documented software development
processes; too many to mention here. However, all
software development processes can be
categorised into:
12
 Sequential Process Models
 Where software is developed in a sequence of stages,
typically: Analyse, Design, Code, Test.
 Iterative Process Models
 Where a sequential process model is repeated until the
software is deemed correct. Typically used when the
requirements for a piece of software are not fully known when
development starts.

13. The Waterfall Model (Sequential)
 While other process models will be
investigated in this module, we will be
focussing upon the central stages of the
Waterfall Model of Software Development.
13
Analysis
Design
Code
Test
Requirements
Softwar
e

14. 14
Analysis (Waterfall Model)
 The analysis phase of software development aims
to develop a requirements specification that can be
used to design the new software system.
 While there is usually more to a requirements
specification, we will be focussing on two of its main
parts:
 Functional Requirements
 First, an abstract definition of what the system must do.
 Then, a detailed set of functional requirements can be
bulleted.
 Non-functional Requirements
 Usually ‘qualitative’ factors such as performance, efficiency
and usability are described.

15. 15
Design (Waterfall Model)
 System design is concerned with how the
system functionality is to be provided by the
different components of the system. It
involves:
 Requirements Partitioning and Identification of
Sub-systems (if any)
 Assign requirements to sub-systems and specify
their functionality
 Define sub-system interfaces

16. 16
Design (Waterfall Model)
 For each sub-system, a detailed design document is
then created.
 It specifies the structural make-up of the sub-system and
were necessary how data is stored, manipulated and
communicated as well as how information is presented.
 Design is often an iterative process, especially in a
system made up of several sub-systems
 As problems identified during the design of one sub-system
can cause the re-design of another.
 Design is typically specified using a mixture of
textual descriptions and structural diagrams.

17. 17
Coding (Waterfall Model)
 Coding can be seen as simply interpreting the
design documents into machine executable
instructions.
 There are many different programming languages
 Factors including the application’s domain will help
in making a choice of which programming language
to use:
 Platform (Hardware, Operating System, Network),
 Programming Paradigm (Object-Oriented/ Function-based/
Event-based)
 Experience of the ‘programmers’ available to do the coding.

18. 18
Testing (Waterfall Model)
 Testing should start as soon as the
requirements specification is available.
 A test plan document should be drawn up in
parallel with the initial design of the system
 The plan uses the requirements to provide an
overall testing strategy for the complete system in
order to satisfy the following conditions:
 Verify – Have we built the system right?
 Validate – Have we built the right system?

19. 19
Testing (Waterfall Model)
 As a more detailed design for each of the
sub-systems is generated, specific testing
strategies for each sub-system can be
designed
 When the code for a sub-system is complete,
specific tests for each sub-system can be
designed based upon the chosen strategy

20. 20

21. Programming Languages and Compilers
are at the core of Computing
All software is written in a programming language
Learning about compilers will teach you a lot about the
programming languages you already know.
Compilers are big – therefore you need to apply all you knowledge
of software engineering.
The compiler is the program from which all other programs arise.

22. Programming Language Concepts
What is a programming language?
Why are there so many programming
languages?
What are the types of programming
languages?
Does the world need new languages?

23. What is a Programming Language
A programming language is a set of rules
that provides a way of telling a computer
what operations to perform.
A programming language is a set of rules
for communicating an algorithm
It provides a linguistic framework for
describing computations

24. What is a Programming Language
English is a natural language. It has words,
symbols and grammatical rules.
A programming language also has words,
symbols and rules of grammar.
The grammatical rules are called syntax.
Each programming language has a different
set of syntax rules.

25. Why Are There So Many
Programming Languages
 Programming languages have evolved over
time as better ways have been developed to
design them.
First programming languages were developed in
the 1950s
Since then thousands of languages have been
developed
 Different programming languages are
designed for different types of programs.

26. Levels of Programming Languages
High-level program class class Triangle Triangle {
{
...
float surface()
...
float surface()
return b*h/2;
}
return b*h/2;
}
Low-level program LOAD r1,b
LOAD r1,b
LOAD r2,h
MUL r1,r2
DIV r1,#2
RET
LOAD r2,h
MUL r1,r2
DIV r1,#2
RET
Executable Machine code 0001001001000101
0001001001000101
0010010011101100
10101101001...
0010010011101100
10101101001...

27. What Are the Types of
Programming Languages
First Generation Languages
Second Generation Languages
Third Generation Languages
Fourth Generation Languages
Fifth Generation Languages

28. First Generation Languages
Machine language
– Operation code – such as addition or
subtraction.
– Operands – that identify the data to be
processed.
Machine language is machine dependent as it is
the only language the computer can understand.
Very efficient code but very difficult to write.

29. Second Generation Languages
Assembly languages
Symbolic operation codes replaced binary
operation codes.
Assembly language programs needed to be
“assembled” for execution by the computer. Each
assembly language instruction is translated into
one machine language instruction.
Very efficient code and easier to write.

30. Third Generation Languages
Closer to English but included simple
mathematical notation.
Programs written in source code which must be
translated into machine language programs called
object code.
The translation of source code to object code is
accomplished by a machine language system
program called a compiler.

31. Third Generation Languages
(continued.)
Alternative to compilation is interpretation
which is accomplished by a system program
called an interpreter.
Common third generation languages
FORTRAN
COBOL
C and C++
Visual Basic

32. Fourth Generation Languages
A high level language (4GL) that requires
fewer instructions to accomplish a task
than a third generation language.
Used with databases
Query languages
Report generators
Forms designers
Application generators

33. Fifth Generation Languages
Declarative languages
Functional(?): Lisp, Scheme, SML
Also called applicative
Everything is a function
Logic: Prolog
Based on mathematical logic
Rule- or Constraint-based

34. The principal paradigms
Imperative Programming (C)
Object-Oriented Programming (C++)
Logic/Declarative Programming (Prolog)
Functional/Applicative Programming (Lisp)

35. Programming Languages
Two broad groups
Traditional programming languages
 Sequences of instructions
 First, second and some third generation languages
Object-oriented languages
 Objects are created rather than sequences of
instructions
 Some third generation, and fourth and fifth
generation languages

36. Traditional Programming Languages
FORTRAN
FORmula TRANslation.
Developed at IBM in the mid-1950s.
Designed for scientific and mathematical
applications by scientists and engineers.

37. Traditional Programming Languages
(cont)
COBOL
COmmon Business Oriented Language.
Developed in 1959.
Designed to be common to many different
computers.
Typically used for business applications.

38. Traditional Programming Languages
(cont)
C
Developed by Bell Laboratories in the early
1970s.
Provides control and efficiency of assembly
language while having third generation
language features.
Often used for system programs.
UNIX is written in C.

39. Object-Oriented Programming
Languages (cont)
C++
It is C language with additional features.
Widely used for developing system and
application software.
Graphical user interfaces can be developed
easily with visual programming tools.

40. Object-Oriented Programming
Languages (cont)
JAVA
An object-oriented language similar to C++ that
eliminates lots of C++’s problematic features
Allows a web page developer to create
programs for applications, called applets that
can be used through a browser.
Objective of JAVA developers is that it be
machine, platform and operating system
independent.

41. Special Programming Languages
Scripting Languages
JavaScript and Vb Script
Php and ASP
Perl and Python
Command Languages
sh, csh, bash
Text processing Languages
Latex, Post Script

42. Special Programming Languages
(cont)
HTML
Hyper Text Markup Language.
Used on the Internet and the World Wide Web
(WWW).
Web page developer puts brief codes called
tags in the page to indicate how the page
should be formatted.

43. Special Programming Languages
(cont)
XML
Extensible Markup Language.
A language for defining other languages.

44. Criteria in a good language design
 Writability: The quality of a language that enables a
programmer to use it to express a computation clearly,
correctly, concisely, and quickly.
 Readability: The quality of a language that enables a
programmer to understand and comprehend the nature of
a computation easily and accurately.
 Reliability: The quality of a language that assures a
program will not behave in unexpected or disastrous ways
during execution.
 Maintainability: The quality of a language that eases
errors can be found and corrected and new features
added.

45. Criteria (Continued)
 Generality: The quality of a language that avoids special
cases in the availability or use of constructs and by
combining closely related constructs into a single more
general one.
 Extensibility: The quality of a language that provides
some general mechanism for the user to add new
constructs to a language.