"Failure is not the opposite of success, it's part of it."
I failed the 1337 Piscine.
It hurt. I thought I wasn't cut out for programming. But instead of giving up, I asked myself:
"What if I just kept going anyway?"
So I did. I didn't wait for acceptance. I didn't wait for permission. I grabbed the 42 curriculum, opened up my terminal, and started building libft — the first project in the 42 network.
No teachers. No peers. Just me, the C documentation, and a lot of segmentation faults.
This repository is proof that you don't need to be accepted into 42 to learn like a 42 student. You just need to start.
libft is a custom implementation of essential C standard library functions. It's the foundation project at 42 School — designed to teach you:
- 🧠 How C actually works under the hood
- 📍 Pointers and memory management (malloc, free, memory leaks)
- 🧱 Modular programming (writing reusable code)
- ⚙️ Makefiles and compilation pipelines
- 🐛 Debugging (valgrind, gdb, and patience)
Instead of relying on <string.h> or <stdlib.h>, you rebuild them yourself. Every function. Every edge case. Every bug.
It's brutal. It's frustrating. And it's exactly what you need to understand C deeply.
ft_isalpha— checks if character is alphabeticft_isdigit— checks if character is a digitft_isalnum— checks if character is alphanumericft_isascii— checks if character is ASCIIft_isprint— checks if character is printableft_toupper— converts to uppercaseft_tolower— converts to lowercase
ft_strlen— calculates string lengthft_strchr— locates character in stringft_strrchr— locates character in string (from the end)ft_strncmp— compares two strings up to n bytesft_strlcpy— copies string with size limitft_strlcat— concatenates string with size limitft_strnstr— locates substring in stringft_strdup— duplicates string (malloc)ft_substr— extracts substringft_strjoin— concatenates two strings (malloc)ft_strtrim— trims characters from both endsft_split— splits string by delimiter (malloc)ft_itoa— converts integer to string (malloc)ft_strmapi— applies function to each characterft_striteri— applies function to each character (with index)
ft_memset— fills memory with constant byteft_bzero— zeros out memoryft_memcpy— copies memory areaft_memmove— copies memory (handles overlap)ft_memchr— locates byte in memoryft_memcmp— compares memory areasft_calloc— allocates and zeros memory
ft_atoi— converts string to integer
ft_putchar_fd— outputs character to file descriptorft_putstr_fd— outputs string to file descriptorft_putendl_fd— outputs string + newline to file descriptorft_putnbr_fd— outputs integer to file descriptor
✅ Pointers are not scary — they're just addresses. Once you understand that, everything clicks.
✅ Memory management is critical — every malloc needs a free. Valgrind is your best friend.
✅ Edge cases matter — NULL pointers, empty strings, size 0... handle them all.
✅ Makefiles automate builds — make, make clean, make fclean, make re.
✅ Reading man pages is a superpower — man 3 strlen teaches you more than any tutorial.
✅ Debugging takes patience — segfaults will test you. Print statements and gdb will save you.
🔥 You don't need permission to learn — failing the Piscine doesn't mean you can't code.
🔥 Struggle is growth — if it's hard, you're learning.
🔥 Build in public — sharing your code makes you accountable and helps others.
🔥 Self-teaching is a skill — no one is coming to save you. Figure it out.
git clone https://github.com/yourusername/libft.git
cd libftmakeThis creates libft.a — a static library you can link to your projects.
In your C file:
#include "libft.h"
int main(void)
{
char *str = ft_strdup("Hello from libft!");
ft_putendl_fd(str, 1);
free(str);
return (0);
}Compile and link:
gcc -Wall -Wextra -Werror main.c -L. -lft -o program
./programmake clean # removes object files
make fclean # removes object files and libft.a
make re # recompiles everything from scratchI included a comprehensive test file: test_libft.c
make
gcc -Wall -Wextra -Werror test_libft.c -L. -lft -o test_libft
./test_libftYou'll see:
- ✅ Green checkmarks for passing tests
- ❌ Red X marks for failing tests
- A final summary with pass/fail count
Use these amazing community testers:
- Tripouille/libftTester — comprehensive and strict
- jtoty/Libftest — classic and thorough
- alelievr/libft-unit-test — detailed output
# Example with Tripouille
git clone https://github.com/Tripouille/libftTester.git
cd libftTester
makeAlways check for leaks:
valgrind --leak-check=full ./test_libftlibft/
├── Makefile # Build automation
├── libft.h # Header file with function prototypes
├── ft_*.c # All function implementations
├── test_libft.c # Comprehensive test suite
└── README.md # This file
All functions are compiled with:
-Wall -Wextra -WerrorTranslation: No warnings. No compromises. Clean code or it doesn't compile.
This project follows the 42 Norm, which enforces:
- Max 25 lines per function
- Max 5 functions per file
- No
forloops (onlywhile) - Specific naming conventions
- No memory leaks, no segfaults
Use norminette to check:
norminette *.c *.hNow that I've built libft, I'm using it as a foundation for:
- 🐚 get_next_line — reading files line by line
- 🖨️ ft_printf — custom printf implementation
- 🐚 minishell — building a bash-like shell
- 🧮 push_swap — algorithm optimization challenges
This is just the beginning.
If you're reading this because you failed Piscine and you're wondering if you should keep going...
Keep going.
You don't need a school to validate your learning. You don't need acceptance to start building. You just need:
- A computer
- A compiler
- The decision to not give up
I failed. I kept coding. And now I have a working C library that I built from scratch.
You can too.
The 42 curriculum is open source. The knowledge is free. The only thing stopping you is you.
So open your terminal, clone this repo, break it, fix it, and make it yours.
Welcome to the real Piscine — the one that never ends.
Found a bug? Have a suggestion? Want to add a feature?
Feel free to open an issue or submit a pull request. This project is a learning tool — let's make it better together.
This project is open source and available under the MIT License.
Use it. Learn from it. Build on it.