C Programming Basics and Fundamentals

Introductory Concepts and C Fundamentals

• Programming languages translate human-readable instructions into machine code for computer execution. Machine language is binary. Assembly language uses mnemonic codes. High-level languages, like C, are easier to write and read. Scripting languages are for automating tasks.
• C is a procedural language, often used for system programming (OS development, embedded systems). It combines low-level capabilities (memory management) with high-level programming features.
• A "Hello, World!" program in C is: #include <stdio.h>; int main() { printf("Hello, World!"); return 0; }
• Desirable characteristics of a program include readability (clear code, comments, good names), efficiency (optimal algorithms), modularity (reusable functions), and portability (runs on different platforms with few changes).

C Fundamentals

• The C character set includes letters, digits, symbols, and white space (spaces, tabs, newlines).
• Identifiers in C are names (e.g., myVar, _count) that start with a letter or underscore.
• Keywords are reserved words (e.g., int, for, return).
• Basic data types include int (integers), float (decimals), char (characters), double (high-precision decimals).
• const or #define creates constants (unchanging values). Example: #define PI 3.14; const int max = 100;.
• Variables store data. Example: int age;.
• Declarations announce variables. Expressions combine variables, operators, and values (e.g., a + b * c). Statements are complete instructions. Example: int sum = a + b;.
• Symbols represent constants (like PI) with meaningful names.

Operators, Expressions, and I/O

• Arithmetic operators perform calculations (+, -, *, /, %).
• Unary operators operate on a single operand (++, --, !).
• Relational operators compare values (>, >=, <, <=, ==, !=).
• Logical operators combine conditions (&&, ||, !).
• Assignment operators assign values (=, +=, -=, etc.).
• Precedence and associativity determine how operators are evaluated.

Data Input and Output

• getchar() reads a single character, putchar() prints one.
• scanf() reads formatted input from the keyboard. printf() displays formatted output to the screen.
• gets() (deprecated) reads a string from the keyboard. puts() displays a string.

Control Statements and Arrays

• Branching includes if-else statements for conditional execution. switch compares a value to multiple possible choices.
• Looping includes for (known iterations), while (condition-based), and do-while (execute at least once). break exits a loop, continue skips the current iteration. goto jumps to a labeled part of the program.
• Arrays let you store multiple values of the same type.
• Multidimensional arrays store data in rows and columns.
• Strings are arrays of characters, terminated by \0.

Functions and Pointers

• Functions are reusable blocks of code.
• Pointers hold memory addresses.