libft

A custom C library developed as part of the 42 curriculum. libft is a small static library that reimplements part of the standard C library and adds a few utility functions that became useful again in later projects.

It was a good way to build solid foundations in low-level C, especially around memory handling, string manipulation, pointers and writing reusable code.

Features

• Reimplementation of common libc-style functions
• Additional string and memory utilities
• Bonus singly linked list helpers
• Static library build with make

Project structure

• libft.h — header file with prototypes and t_list definition
• ft_*.c — function implementations
• Makefile — builds the libft.a static library

Mandatory part

The mandatory part covers the core utility functions used throughout the project.

Character checks and conversions

• ft_isalpha — checks whether a character is alphabetic
• ft_isdigit — checks whether a character is a digit
• ft_isalnum — checks whether a character is alphanumeric
• ft_isascii — checks whether a character belongs to the ASCII table
• ft_isprint — checks whether a character is printable
• ft_toupper — converts a lowercase letter to uppercase
• ft_tolower — converts an uppercase letter to lowercase

Memory functions

• ft_memset — fills a memory area with a byte value
• ft_bzero — sets a memory area to zero
• ft_memcpy — copies memory from one buffer to another
• ft_memmove — copies memory safely, including overlapping regions
• ft_memchr — finds the first occurrence of a byte in memory
• ft_memcmp — compares two memory areas
• ft_calloc — allocates zero-initialized memory

String functions

• ft_strlen — returns the length of a string
• ft_strlcpy — copies a string into a sized buffer
• ft_strlcat — concatenates a string into a sized buffer
• ft_strchr — finds the first occurrence of a character in a string
• ft_strrchr — finds the last occurrence of a character in a string
• ft_strncmp — compares two strings up to n characters
• ft_strnstr — finds a substring within a limited length
• ft_strdup — duplicates a string using dynamic allocation

Conversion and output

• ft_atoi — converts a string to an integer
• ft_putchar_fd — writes a character to a file descriptor
• ft_putstr_fd — writes a string to a file descriptor
• ft_putendl_fd — writes a string followed by a newline
• ft_putnbr_fd — writes an integer to a file descriptor

Additional utility functions

• ft_substr — extracts a substring from a string
• ft_strjoin — joins two strings into a new one
• ft_strtrim — trims a set of characters from both ends of a string
• ft_split — splits a string into an array using a delimiter
• ft_itoa — converts an integer to a string
• ft_strmapi — creates a new string by applying a function to each character
• ft_striteri — applies a function to each character of a string in place

Bonus part

The bonus part adds linked list functions based on the following structure:

typedef struct s_list
{
	void			*content;
	struct s_list	*next;
} t_list;

Linked list functions

• ft_lstnew — creates a new list node
• ft_lstadd_front — adds a node at the beginning of a list
• ft_lstsize — counts the number of nodes in a list
• ft_lstlast — returns the last node of a list
• ft_lstadd_back — adds a node at the end of a list
• ft_lstdelone — deletes one node using a given function
• ft_lstclear — clears an entire list
• ft_lstiter — applies a function to each node content
• ft_lstmap — creates a new list by applying a function to each node

Build

Build the library:

make

Build the bonus part:

make bonus

Clean object files:

make clean

Remove object files and library:

make fclean

Rebuild everything:

make re

Learning outcomes

This project was my first real base in reusable C code. It helped build solid foundations in:

• pointer manipulation
• memory allocation and deallocation
• string processing
• modular code organization
• static library compilation