Page 5 - Computer Science Class 11 Without Functions
P. 5
PREFACE
As we are in an age of digital transformations and technological innovations, you have made the right choice to study Computer
Science as part of the CBSE curriculum. This book will introduce you to the fascinating world of computers. It comprises two
volumes, one for the students in class XI and the other for the students in class XII.
In class XI, we will begin by learning what makes the computer so impactful that it affects all aspects of our lives. In the first
unit, we will learn about the computer hardware and software components of a computer and how they combine to make such
a formidable combination. To communicate with a person, we must know their language. As the computer deals with only
binary information (1’s and 0’s), we will briefly study the binary representation of data and the Boolean algebra of binary values
developed by George Boole.
As the primary purpose of studying Computer Science is to learn to solve our problems using a computer, we will devote the
second unit, which forms a considerable part of the book, to problem-solving using a computer. The task of solving problems
using a computer is often called programming. Although computer only understands the language of 1’s and 0’s, humans find
it inconvenient to give instructions to a computer as sequences of 1’s and 0’s. So, computer scientists have developed several
programming languages, called high-level languages, that are quite close to natural languages. Ultimately, the instructions in a
programming language are translated as binary sequences using either a compiler or an interpreter. In this book, we will learn
Python - a programming language that supports a simple and organised approach to problem-solving.
As old habits die hard, the book encourages the reader to follow good programming practices right from the beginning. We have
made an effort to introduce the programming constructs in the context of the examples that justify the use of those constructs.
We have devoted ten chapters of the book to introduce the fundamental programming concepts (Chapters 4-13). Although
a programming language (like Python) is similar to a natural language, it is not a natural language yet. So, in Chapter 4, we
introduce you to the notions of algorithms, flowcharts, and pseudocodes required for the new way of problem-solving using
a programming language (Python, in our case). Chapters 5-7 cover the basic building blocks of the Python language. As good
documentation is crucial to the success of any software engineering project, we introduce sound practice code documentation
early in the book (Chapter 8) and consistently document the code throughout the book, describing the objective of each piece of
the code and how it interfaces with the rest of the code under discussion so that it gets integrated with the student’s approach
to problem-solving. In the same spirit, we emphasise using the named objects in preference to the ones hard-coded.
As real-life problems usually require non-sequential and repetitive execution of instructions, Chapters 8 and 9 are devoted
to a detailed study of control structures. As successful software development requires the code to be organised in the form
of modules, in Chapter 10, we discuss how to design the modules. Text data is expressed in the form of strings, which is the
subject of Chapter 11. Complex problems require structuring the data in the form of lists, tuples, and dictionaries, as discussed
in Chapters 12 and 13.
While automation has made our lives comfortable, serious concerns about IT infrastructure security and individuals’ privacy rights
have been raised. Chapter 14 discusses these issues and related laws enacted to address security and privacy concerns.
ACKNOWLEDGEMENTS
We are grateful to Drashti Varshney and Nimish Kumar, undergraduate students at Dyal Singh College of the University of Delhi,
for reviewing the entire book with great care and suggesting dozens of subtle corrections and modifications.
We are grateful to the Orange Book team, especially Ms. Nidhi Gupta, who was readily available for help during the book’s
preparation. Last but not least, we would like to express our gratitude to our family members for their support and patience.
Naveen Kumar
Ankit Rajpal
Sheetal Rajpal
Mohini Arora

