Notes

UNIT-1
CHAPTER-1
Introduction
What is a program: -
A program is a set of instruction written in computer
language used for solving a problem. These instructions are
stored in files and tell your computer to perform a task.
Software: Classification of Software
Software is a set of programs, which is designed to perform a well-
defined function.
A program is a sequence of instructions written to solve a particular
problem.
There are two types of software −

 System Software
 Application Software

System Software
The system software is a collection of programs designed to
operate, control, and extend the processing capabilities of the
computer itself.

System software is generally prepared by the computer
manufacturers.

These software products comprise of programs written in low-level
languages, which interact with the hardware at a very basic level.

System software serves as the interface between the hardware and
the end users.

Some examples of system software are Operating System,
Compilers, Interpreter, Assemblers, etc.

,Here is a list of some of the most prominent features of a system
software −

 Close to the system
 Fast in speed
 Difficult to design
 Difficult to understand
 Less interactive
 Smaller in size
 Difficult to manipulate
 Generally written in low-level language

Application Software
Application software products are designed to satisfy a particular
need of a particular environment.
All software applications prepared in the computer lab can come
under the category of Application software.
Application software may consist of a single program, such as
Microsoft's notepad for writing and editing a simple text. It may also
consist of a collection of programs, often called a software package,
which work together to accomplish a task, such as a spreadsheet
package.
Examples of Application software are the following −

 Payroll Software
 Student Record Software
 Inventory Management Software
 Income Tax Software
 Railways Reservation Software
 Microsoft Office Suite Software
 Microsoft Word
 Microsoft Excel

,  Microsoft PowerPoint




Features of application software are as follows −

 Close to the user
 Easy to design
 More interactive
 Slow in speed
 Generally written in high-level language
 Easy to understand
 Easy to manipulate and use
 Bigger in size and requires large storage space
Modular Programming
Modular programming is the process of subdividing a computer
program into separate sub-programs.
A module is a separate software component.
 It can often be used in a variety of applications and functions with
other components of the system.
Similar functions are grouped in the same unit of programming
code and separate functions are developed as separate units of code
so that the code can be reused by other applications.
Object-oriented programming (OOP) is compatible with the
modular programming concept to a large extent.
Modular programming enables multiple programmers to divide up
the work and debug pieces of the program independently.
The benefits of using modular programming include:

 Less code has to be written.
 A single procedure can be developed for reuse, eliminating the
need to retype the code many times.
 Programs can be designed more easily because a small team
deals with only a small part of the entire code.

,  Modular programming allows many programmers to
collaborate on the same application.
 The code is stored across multiple files.
 Code is short, simple and easy to understand.
 Errors can easily be identified, as they are localized to a
subroutine or function.
 The same code can be used in many applications.
 The scoping of variables can easily be controlled.

Structured Programming
C is called a structured programming language because to solve a
large problem, C programming language divides the problem into
smaller structural blocks each of which handles a particular
responsibility.
Structured Programming Approach with Advantages and
Disadvantages:
 Structured Programming Approach, as the word suggests, can be
defined as a programming approach in which the program is
made as a single structure.
 It means that the code will execute the instruction by instruction
one after the other.
 It doesn’t support the possibility of jumping from one
instruction to some other with the help of any statement like
GOTO, etc.
 Therefore, the instructions in this approach will be executed in a
serial and structured manner.
 The languages that support Structured programming approach
are:
 C
 C++
 Java
 C#



The structured program mainly consists of three types of elements:
 Selection Statements
 Sequence Statements
 Iteration Statements
Entry and exit in a Structured program are a single-time event. It
means that the program uses single-entry and single-exit elements.