1. Basics of C Programming

Basic Structure of C Program

A C program consists of header files, main function, variable declarations, and statements. Execution starts from the main() function.

Compilation and Execution of C Program

The source code is compiled using a compiler like GCC, which converts it into machine code, then executed to produce output.

Elements of C Program

• Keywords
• Identifiers
• Constants
• Variables
• Operators
• Statements

Escape Sequences

Escape sequences are special characters used in strings like \n (new line), \t (tab), \" (double quote).

Delimiters

Delimiters are symbols used to separate program elements such as semicolon (;), braces {}, and commas (,).

Keywords

Keywords are reserved words with predefined meaning such as int, float, if, else, return.

Identifiers

Identifiers are names given to variables, functions, or arrays. They must start with a letter or underscore.

Data Types

Data types specify the type of data a variable can store such as int, float, char, double.

Constants

Constants are fixed values that do not change during program execution.

Variables

Variables are named memory locations used to store data.

Expressions

An expression is a combination of operands and operators that evaluates to a value.

Statements

Statements are instructions given to the compiler to perform an action.

Expression Statements

Expression statements evaluate an expression such as assignment or function call.

Comments

Comments are used to explain code and are ignored by the compiler. They can be single-line or multi-line.

2. Operators and Expressions

Arithmetic Operators

Used for mathematical operations like +, -, *, /, and %.

Assignment Operators

Used to assign values to variables such as =, +=, -=.

Increment and Decrement Operators

Used to increase or decrease a value by one (++ and --).

Relational Operators

Used to compare two values like <, >, <=, >=, ==, !=

Logical Operators

Used to combine conditions such as &&, ||, !

Conditional (Ternary) Operator

A shorthand for if-else condition using ?: operator.

Sizeof Operator

Returns the size of a data type or variable in bytes.

Comma Operator

Allows multiple expressions to be evaluated sequentially.

Bitwise Operators

Operate on binary bits like &, |, ^, ~, <<, >>.

Type Conversion

Converts one data type to another automatically or manually.

Operator Precedence and Associativity

Defines the order in which operators are evaluated in an expression.

3. Control Statements

If-Else

Executes code based on a condition.

Nested If-Else

If-else statements inside another if-else.

Else If Ladder

Used to check multiple conditions sequentially.

For Loop

Used when the number of iterations is known.

While Loop

Repeats execution while a condition is true.

Do-While Loop

Executes code at least once before checking condition.

Nested Loops

A loop inside another loop.

Break

Terminates the loop or switch statement.

Continue

Skips the current iteration of a loop.

Goto

Transfers control to a labeled statement.

Switch Statement

Used to execute one case from multiple options.

4. Functions

Function with Parameters

Functions that accept input values.

No Arguments No Return Value

Function that neither takes input nor returns output.

Arguments with Return Value

Function that accepts input and returns a value.

No Argument with Return Value

Function that returns a value without taking input.

Local Variable

Declared inside a function and accessible only within it.

Global Variable

Declared outside functions and accessible throughout the program.

Static Variable

Preserves its value between function calls.

Call by Value and Call by Reference

Call by value passes copy, call by reference passes address.

5. Recursion

Recursion is a process where a function calls itself until a base condition is met.

6. Arrays

Types of Arrays

Arrays can be single, multi-dimensional, or dynamic.

Single Dimensional Array

Stores elements in a linear format.

Two Dimensional Array

Stores data in rows and columns.

Three Dimensional Array

Used to store data in 3D format.

Dynamic Array

Memory allocated at runtime using malloc or calloc.

Pointer Array

Array of pointers.

Constant Array

Array whose values cannot be modified.

7. Pointers

Pointer Basics

Pointers store memory addresses of variables.

Pointer Arithmetic

Used to navigate memory locations.

Pointers and Arrays

Array name acts as a pointer to the first element.

Function Pointers

Pointers that store function addresses.

Void Pointer

Generic pointer that can store address of any type.

8. Strings

String Handling

Strings are arrays of characters terminated by null character.

String Functions

• strlen()
• strcat()
• strcpy()
• strcmp()
• strchr()

9. Structures and Unions

Structure

Used to group different data types.

Union

Stores different data types in same memory location.

Typedef

Creates alias for data types.

12. File Handling

File Operations

Used to store data permanently using files.

File Modes

Common modes are r, w, a, a+.

Command Line Arguments

Used to pass arguments during program execution.

13. Featured Concepts

Preprocessor

Handles macros and header files.

Enum

Used to define named constants.

Const and Volatile

Const prevents modification, volatile prevents optimization.

Scope and Storage Class

Defines visibility and lifetime of variables.

Stack and Queue

Linear data structures used for data storage.