Introduction

C is one of the most widely used programming languages in the world, and it is the language every Karnataka 2nd PUC Electronics student meets first when learning to make a computer do useful work. It sits close to the machine, yet reads almost like ordinary structured text — which is exactly why it is used both to build system software (operating systems, compilers, device drivers) and everyday application programs.

This chapter builds the C foundation you need for the II PUC board exam, step by step. It begins with how a complete C program is organised, then works through the smallest pieces the language is made of and how they combine:

• how a C program is structured, and the role of the main() function, comments and the C preprocessor (#define, #include);
• the building blocks called tokens — keywords, identifiers, constants, strings, operators and special symbols;
• variables and data types, how memory is reserved for them, and how values are stored;
• operators (arithmetic, relational, logical, bitwise, assignment, conditional, increment/decrement) and the precedence rules that decide the order of evaluation;
• type conversion (type casting); and
• managing input and output with scanf() and printf(), including format specifiers.

Master this section and you will be ready for the decision-making, branching and looping statements that follow later in the chapter. Everything here is written for the KTBS II PUC Electronics syllabus — a state Electronics course — so the treatment stays close to what your prescribed textbook covers, in our own words.