C Programming Basics

• C programming is a general-purpose, procedural computer programming language supporting structured programming, lexical variable scope, and recursion.

Key features of C programming

• Procedural: Programs are built from procedures or functions.
• Imperative: Instructions tell the computer exactly what to do.
• Structure: Provides mechanisms like structs to group data.
• Lexical scope: Variables are accessible within a specific region of code.
• Recursion: Functions calling themselves to solve subproblems.
• Low-level memory access: Allows direct manipulation of memory locations.

Data types in C

• Fundamental data types:
  • int: Integer values.
  • float: Floating-point numbers.
  • double: Double-precision floating-point numbers.
  • char: Character values.
  • void: Represents the absence of a type.
• Derived data types:
  • Arrays: Ordered collections of elements of the same type.
  • Pointers: Variables storing memory addresses.
  • Structures: Groups of variables of different types under one name.

Operators in C

• Arithmetic operators: +, -, *, /, %.
• Relational operators: ==, !=, >, <, >=, <=.
• Logical operators: &&, ||, !.
• Bitwise operators: &, |, ^, ~, <<, >>.
• Assignment operators: =, +=, -=, *=, /=, %=, &=, |=, ^=, <<=, >>=.

Control flow statements

• Conditional statements:
  • if, else if, else.
  • switch statement.
• Looping statements:
  • for loop.
  • while loop.
  • do-while loop.

Functions in C

• Defining a function: Specifies the function's name, parameters, and return type.
• Calling a function: Invoking a function using its name and arguments.
• Return values: Functions can return a value or nothing (void).
• Function prototypes: Declaration of a function's parameters and return type.
• Function advantages: Reusability, modularity, and code maintainability.

Input/Output in C

• Standard input/output:
  • scanf function for reading input from the console.
  • printf function for printing output to the console.
• File input/output:
  • fopen for opening files.
  • fclose for closing files.
  • fprintf, fscanf for file I/O.

Memory management in C

• Dynamic memory allocation:
  • malloc, calloc, realloc, free for allocating memory during runtime.
• Memory leaks: Potential issues when failing to free allocated memory.

Pointers in C

• Address operator (&): Returns the memory address of a variable.
• Indirection operator (*): Accesses the value at the memory address pointed to by the variable.
• Pointer arithmetic: Allows mathematical operations on addresses stored in pointers.
• Pointers in arrays: Accessing elements of an array using pointers.
• Pointers and strings: Strings can be treated as arrays of characters.

Arrays in C

• Declaration: Declaring an array with a specific size (e.g., int numbers[10];).
• Accessing elements: Accessing array elements using indices starting from 0 (e.g., numbers[0]).
• Multidimensional arrays: Arrays with more than one dimension.
• Array advantages: Storing and manipulating a collection of data items of the same type in a sequential manner.

Structures in C

• Defining structures: Declaring a new data type that groups related variables.
• Accessing members: Accessing structure members using the dot operator (.) or arrow operator (->).
• Structure advantages: Bundling of logically related data items.

Common C programming errors

• Syntax errors: Incorrect use of keywords and operators.
• Logic errors: Errors in the program's algorithm.
• Memory management errors: Problems with allocating and deallocating memory.
• Input validation errors: Failing to validate input for expected types.

Preprocessor directives

• #include: Includes header files.
• #define: Defines constants or macros.
• #ifdef, #ifndef, #endif: Conditional compilation.

Example of a Simple C Program

#include <stdio.h>

int main() {
    int x = 10;
    int y = 20;
    int sum = x + y;
    printf("The sum is: %d\n", sum);
    return 0;
}