This project has been created as part of the 42 curriculum by ahideo-k.

Libft

Description

Libft is the first core project of the 42 Common Core. Its objective is to recreate a subset of the C Standard Library while implementing additional utility functions that will be reused throughout the curriculum.

This project reinforces fundamental concepts of the C language, including:

• Memory management
• Pointer manipulation
• String handling
• Character classification
• Linked lists
• Modular programming
• Static libraries
• Defensive programming

The final result is a static library (libft.a) containing reusable functions that serve as the foundation for future projects such as get_next_line, ft_printf, so_long, pipex, push_swap, and many others.

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Library Overview

The library is divided into three main parts.

Part 1 – Libc Functions

Reimplementation of standard C library functions without relying on the original implementations.

Character functions

• ft_isalpha
• ft_isdigit
• ft_isalnum
• ft_isascii
• ft_isprint
• ft_toupper
• ft_tolower

String functions

• ft_strlen
• ft_strlcpy
• ft_strlcat
• ft_strchr
• ft_strrchr
• ft_strncmp
• ft_strnstr
• ft_strdup

Memory functions

• ft_memset
• ft_bzero
• ft_memcpy
• ft_memmove
• ft_memchr
• ft_memcmp
• ft_calloc

Conversion

• ft_atoi

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Part 2 – Additional Functions

Utility functions frequently used in later projects.

• ft_substr
• ft_strjoin
• ft_strtrim
• ft_split
• ft_itoa
• ft_strmapi
• ft_striteri
• ft_putchar_fd
• ft_putstr_fd
• ft_putendl_fd
• ft_putnbr_fd

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Part 3 – Linked List Functions

Implementation of a generic singly linked list.

• ft_lstnew
• ft_lstadd_front
• ft_lstsize
• ft_lstlast
• ft_lstadd_back
• ft_lstdelone
• ft_lstclear
• ft_lstiter
• ft_lstmap

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Project Structure

.
├── Makefile
├── libft.h
├── *.c
└── README.md

The project generates the static library:

libft.a

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Instructions

Clone the repository

git clone https://github.com/Andre-Kikuchi/libft.git
cd libft

Compile

Compile the library:

make

Clean object files:

make clean

Remove object files and the library:

make fclean

Rebuild everything:

make re

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Using the Library

Include the header:

#include "libft.h"

Compile your project linking against the library:

cc main.c libft.a

Example:

#include "libft.h"

int main(void)
{
    ft_putendl_fd("Hello, Libft!", 1);
    return (0);
}

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Technical Choices

This project follows the requirements established by the 42 subject.

• Written entirely in C
• Compiled with cc
• Flags:
  • -Wall
  • -Wextra
  • -Werror
• No global variables
• Helper functions declared as static whenever appropriate
• Static library generated using ar
• Code compliant with the 42 Norm

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Learning Outcomes

Through this project I practiced:

• Memory allocation with malloc
• Safe memory manipulation
• Pointer arithmetic
• String processing
• Defensive programming
• Modular software design
• Static libraries
• Linked list manipulation
• Writing reusable code

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Resources

Documentation

• The C Programming Language — Brian W. Kernighan & Dennis M. Ritchie
• Linux Manual Pages (man)
• Understanding and Using C Pointers-O'Reilly Media (2013) - Richard Reese
• Linked List in C - GeeksforGeeks
• GNU C Library Documentation

Useful websites:

• https://man7.org/linux/man-pages/
• https://beej.us/guide/bgc/

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AI Usage

Artificial Intelligence was used only as a learning support tool.

Specifically, it was used to:

• clarify concepts about pointer manipulation;
• review edge cases;
• better understand the behavior of standard C library functions;
• improve documentation.

All code was designed, implemented, tested, debugged and understood before submission.

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License

This project was developed as part of the 42 curriculum and is intended for educational purposes.