🧩 Libft

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📑 Table of Contents

• About the Project
• Features
• Compilation
• How It Works

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🏫 About the Project

Libft is the first project in the 42 curriculum. It consists of recreating a simplified version of the C standard library and implementing additional utility functions that will be reused in future projects.

It reinforces fundamental programming concepts:

• Memory management (malloc, free)
• String and array manipulation
• Use of static libraries
• Function pointers and modular design
• Linked list data structures (bonus part)

The project is written in accordance with the 42 Norm, ensuring clean, readable, and maintainable code.

Peer-graded at 42Barcelona with a final grade of 125/100, including the bonus.

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🚀 Features

Libft is divided into three main sections: Libc functions, Additional functions, and Bonus (linked list).

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📘 Libc Functions

These functions replicate the behavior of the standard C library (libc). For detailed descriptions, check their corresponding man pages (e.g. man strlen, man memcpy, etc.).

Character checks

• ft_isalpha — Checks if a character is alphabetic.
• ft_isdigit — Checks if a character is a digit (0–9).
• ft_isalnum — Checks if a character is alphanumeric.
• ft_isascii — Checks if a character is within the ASCII range.
• ft_isprint — Checks if a character is printable.

Memory functions

• ft_memset — Fills a block of memory with a specific byte.
• ft_bzero — Zeros out a block of memory.
• ft_memcpy — Copies bytes from one memory area to another.
• ft_memmove — Safely copies overlapping memory regions.
• ft_memchr — Scans memory for a specific byte.
• ft_memcmp — Compares two memory areas.
• ft_calloc — Allocates and zeros memory for an array.

String manipulation

• ft_strlen — Returns the length of a string.
• ft_strlcpy — Copies a string into a destination buffer with size limit.
• ft_strlcat — Appends one string to another with size limit.
• ft_strdup — Duplicates a string in newly allocated memory.
• ft_strchr — Locates the first occurrence of a character in a string.
• ft_strrchr — Locates the last occurrence of a character in a string.
• ft_strnstr — Searches for a substring within a string up to a given length.
• ft_strncmp — Compares two strings up to a given number of characters.

Conversions

• ft_atoi — Converts a string to an integer.
• ft_toupper — Converts a lowercase letter to uppercase.
• ft_tolower — Converts an uppercase letter to lowercase.

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🧩 Additional Functions

Functions not included in libc, but essential for working with dynamic strings and memory in C projects.

String and memory utilities

• ft_substr — Extracts a substring from a string.
• ft_strjoin — Concatenates two strings into a new one.
• ft_strtrim — Removes specified characters from the beginning and end of a string.
• ft_split — Splits a string into an array of strings using a delimiter.
• ft_itoa — Converts an integer to a string.
• ft_strmapi — Applies a function to each character of a string (returns a new string).
• ft_striteri — Applies a function to each character of a string in place.

File descriptor output

• ft_putchar_fd — Outputs a character to a given file descriptor.
• ft_putstr_fd — Outputs a string to a given file descriptor.
• ft_putendl_fd — Outputs a string followed by a newline to a file descriptor.
• ft_putnbr_fd — Outputs an integer to a given file descriptor.

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🪴 Bonus Part (Linked Lists)

Implements a basic linked list library using the t_list structure:

• ft_lstnew — Creates a new list node.
• ft_lstadd_front — Adds a new node at the beginning of the list.
• ft_lstsize — Returns the number of nodes in the list.
• ft_lstlast — Returns the last node of the list.
• ft_lstadd_back — Adds a new node at the end of the list.
• ft_lstdelone — Deletes a single node using a given function.
• ft_lstclear — Deletes and frees an entire list.
• ft_lstiter — Iterates over the list, applying a function to each element.
• ft_lstmap — Creates a new list by applying a function to each element of another list.

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🛠️ Compilation

Compile the library using:

make

This will generate libft.a, a static library containing all implemented functions.

To include the bonus (linked list) functions:

make bonus

To clean object files:

make clean

To remove everything (including the library):

make fclean

To recompile from scratch:

make re

You can use libft in any C project by including its header and linking the library:

#include "libft.h"

Compile your program either with:

cc main.c -L. -lft -I. -Wall -Wextra -Werror -o prog

or

cc -Wall -Wextra -Werror main.c libft.a -o prog

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🧠 How It Works

Every function in libft is implemented from scratch, mimicking the behavior of standard C functions while adhering to the 42 Norm. This project strengthens your understanding of:

• Low-level memory operations
• Pointer arithmetic
• Efficient data manipulation
• Safe and modular C design

The bonus linked list section introduces dynamic data structures, highlighting proper memory allocation, traversal, and cleanup — essential skills for advanced C projects at 42.