This book is intended for anyone, who is interested in knowing about computers and basics of C. We are extremely happy to come out with this book on "Expertise your C" for students of all the streams in Computer Applications. I have divided the syllabus into the small chapters so that the topics can be arranged properly. The topics within the chapters have been arranged in a proper sequence to ensure smooth flow of the subject. The book has been thoughtfully structured to serve as an ideal textbook for various courses offered in computer science. We thankful to great Almighty and especially to our parents for the encouragement and support that they have extended. We have made every possible effort to eliminate all the errors in this book. However if you find any, please let us know, that will improve us further.