> ## Documentation Index
> Fetch the complete documentation index at: https://learn.acadlink.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction to C

> History, features, and versions of the C programming language

# C Programming Introduction

C is a **general-purpose, procedural programming language** developed by **Dennis Ritchie** in **1972** at Bell Laboratories. It follows a step-by-step approach and uses functions to perform tasks.

C is known for its **speed, efficiency, and closeness to hardware**, making it ideal for system-level programming — operating systems, embedded systems, and compilers are all built with C. Programs in C are written using English-like statements and can run on almost any computer, making it highly **portable**.

***

## History of C

The lineage of C traces through several languages:

* **1960 — ALGOL**: First language to use a block structure.
* **1967 — BCPL**: Developed by Martin Richards, derived from ALGOL.
* **1970 — B**: Created by Ken Thompson using BCPL. Both BCPL and B were type-less.
* **1972 — C**: Developed by Dennis Ritchie at Bell Labs using BCPL and B.

***

## Why Learn C?

* Foundation for C++, Java, Python, and most modern languages.
* Used in OS kernels, microcontrollers, game engines, and databases.
* Teaches low-level memory management and hardware interaction.
* Fast execution with minimal abstraction overhead.

***

## C Language Versions

| Version      | Year | Key Features                               |
| ------------ | ---- | ------------------------------------------ |
| K\&R C       | 1978 | First version, by Kernighan & Ritchie      |
| ANSI C / C89 | 1989 | First standardized version                 |
| C90          | 1990 | International standard of ANSI C           |
| C95          | 1995 | Added `wchar_t`                            |
| C99          | 1999 | `inline`, `//` comments, `long long int`   |
| C11          | 2011 | Multithreading, `_Atomic`, safer functions |
| C17          | 2018 | Bug fixes and clarifications               |
| C23 (latest) | 2024 | Better Unicode, type inference             |

***

## Structure of a C Program

```c theme={null}
#include <stdio.h>    // Preprocessor directive

int main() {          // Entry point of every C program
    printf("Hello, World!\n");
    return 0;
}
```

| Component            | Purpose                                        |
| -------------------- | ---------------------------------------------- |
| `#include <stdio.h>` | Includes the standard input/output library     |
| `int main()`         | Every C program starts executing from `main()` |
| `printf()`           | Prints output to the screen                    |
| `return 0`           | Returns 0 to indicate successful execution     |