C Fundamentals

A hands-on exploration of C from the ground up — memory, pointers, data structures, algorithms, and systems programming.

The goal is not just to write programs but to understand what happens at the machine level. Every program here is written with that intent.

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Directory Structure

c-fundamentals/
├── standard_library_implementations/
│   ├── strlen.c
│   ├── memcpy.c
│   ├── memmove.c                         ← todo
│   ├── strcpy.c                          ← todo
│   ├── strcat.c                          ← todo
│   └── malloc.c                          ← todo (ambitious but impressive)
│
├── data_structures/
│   ├── linked_list.c                     ← todo
│   ├── doubly_linked_list.c              ← todo
│   ├── stack.c                           ← todo
│   ├── queue.c                           ← todo
│   ├── hash_map.c                        ← todo
│   └── dynamic_array.c                   ← todo
│
├── algorithms/
│   ├── bubble_sort.c                     ← todo
│   ├── insertion_sort.c                  ← todo
│   ├── binary_search.c                   ← todo
│   ├── merge_sort.c                      ← todo
│   ├── quick_sort.c                      ← todo
│   └── generic_sort.c
│
├── systems/
│   ├── file_programming/
│   ├── network_programming/
│   │   ├── http_server.c                 ← todo
│   │   └── multithreaded_http_server.c   ← todo
│   └── commandline_tools/
│
├── memory_and_pointers/
│   ├── pointer_arithmetic.c              ← todo
│   ├── struct_memory_layout.c            ← todo
│   ├── generic_functions.c               ← todo
│   └── function_pointers.c               ← todo
│
└── projects/
    └── markdown_parser.c                 ← currently working on it

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Standard Library Implementations

Reimplementing standard library functions from scratch to understand what the abstractions are hiding.

File	Description	Status
strlen.c	Counts bytes in a string by walking memory until \0	✅ Done
memcpy.c	Copies n bytes from source to destination using void pointers	✅ Done
memmove.c	Like memcpy but handles overlapping memory regions	🔲 Todo
strcpy.c	Copies a string including the null terminator	🔲 Todo
strcat.c	Concatenates two strings	🔲 Todo
malloc.c	Simple memory allocator	🔲 Todo

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Data Structures

Implementing fundamental data structures using raw memory and pointers.

File	Description	Status
linked_list.c	Singly linked list with insert, delete, search	🔲 Todo
doubly_linked_list.c	Linked list that traverses both directions	🔲 Todo
stack.c	LIFO data structure using linked list	🔲 Todo
queue.c	FIFO data structure using linked list	🔲 Todo
hash_map.c	Hash map with collision handling	🔲 Todo
dynamic_array.c	Vector-like growable array using realloc	🔲 Todo

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Algorithms

File	Description	Status
bubble_sort.c	Simple comparison sort	🔲 Done
insertion_sort.c	Efficient for small or nearly sorted data	🔲 Done
binary_search.c	O(log n) search on sorted arrays	🔲 Done
generic_sort.c	Sorting any data type using void pointers and function pointers	🔲 Done
merge_sort.c	Divide and conquer sorting	🔲 Todo
quick_sort.c	The algorithm behind the standard library qsort	🔲 Todo

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Systems Programming

Programs that interact directly with the operating system.

File I/O

Reading, writing, and parsing structured data from files.

Network Programming

File	Description	Status
http_server.c	Serves static files over TCP	🔲 Done
multithreaded_http_server.c	Handles concurrent connections	🔲 Todo

Command Line Tools

Tools that read from stdin, process data, and write to stdout.

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Memory and Pointers

Programs that demonstrate deep pointer and memory understanding.

File	Description
pointer_arithmetic.c	Walking arrays and strings with pointer math
struct_memory_layout.c	Padding, alignment, and offsetof
generic_functions.c	Writing functions that work on any type using void pointers
function_pointers.c	Passing behavior as data

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Parsers

File	Description	Status
markdown_parser.c	Parses markdown and converts to HTML	🔲 Todo

The markdown parser is the most ambitious project in this repo — it combines string handling, memory management, file I/O, and pointers into one real, useful program.

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What I Learned

C forces you to think about things most languages hide:

• There are no strings — just pointers to bytes ending in \0
• There are no generics — you use void pointers and function pointers
• There is no automatic memory — you allocate and free manually
• Every abstraction has a cost you can measure and understand

This understanding carries into every other language and makes you a better programmer regardless of what you write in.

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Build

Each program is self contained and compiles with:

gcc -Wall -Wextra -o output filename.c