This project has been created as part of the 42 curriculum by mamatter.

Description

Libft is my first C library. It rebuilds common libc functions and adds useful extra ones. I will reuse it in my future 42 projects.

The library has three parts:

• Part 1: libc functions, renamed with the ft_ prefix.
• Part 2: extra functions for strings, numbers and output.
• Part 3: functions to handle linked lists.

Instructions

Build the library with make. It creates libft.a at the root of the repository.

make        # build libft.a
make clean  # remove object files
make fclean # remove object files and libft.a
make re     # rebuild everything

Use the library with your own main

1. Include the header in your main.c:

#include "libft.h"

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

2. Build the library, then compile your main.c and link it with libft.a:

make
cc -Wall -Wextra -Werror main.c -L. -lft -o test
./test

• -L. tells the compiler to look for libraries in the current directory.
• -lft links libft.a (the lib prefix and .a extension are implied).
• If libft.h is in another folder, add -I path/to/folder.

If your main.c is outside the repository, adapt the paths:

cc -Wall -Wextra -Werror main.c -I path/to/libft -L path/to/libft -lft -o test

Library description

Part 1 - Libc functions

Each function works like the original, as described in its man page.

Function	What it does
ft_isalpha	Checks if a character is a letter.
ft_isdigit	Checks if a character is a digit.
ft_isalnum	Checks if a character is a letter or a digit.
ft_isascii	Checks if a value is in the ASCII table (0 to 127).
ft_isprint	Checks if a character is printable.
ft_toupper	Turns a lowercase letter into uppercase.
ft_tolower	Turns an uppercase letter into lowercase.
ft_strlen	Returns the length of a string.
ft_strcpy	Copies a string into a buffer.
ft_strcat	Appends a string at the end of another.
ft_strlcpy	Copies a string into a buffer without overflowing it.
ft_strlcat	Appends a string to another without overflowing the 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_strncpy	Copies a string into a buffer, up to n characters.
ft_strnstr	Finds a substring in a string, within len characters.
ft_strdup	Returns a new copy of a string.
ft_atoi	Converts the start of a string into an int.
ft_memset	Fills a memory area with one byte.
ft_bzero	Sets a memory area to zero.
ft_memcpy	Copies bytes from one area to another.
ft_memmove	Copies bytes and handles overlapping areas safely.
ft_memchr	Finds a byte in a memory area.
ft_memcmp	Compares two memory areas.
ft_calloc	Allocates memory and sets it to zero.

Part 2 - Additional functions

Function	What it does
ft_substr	Returns a new string cut from a given position and length.
ft_strjoin	Returns a new string made of two strings put together.
ft_strtrim	Returns a copy of a string without the chosen characters at both ends.
ft_split	Cuts a string at each delimiter and returns an array of strings.
ft_itoa	Converts an integer into a string.
ft_strmapi	Applies a function to each character and returns the new string.
ft_striteri	Applies a function to each character of a string, in place.
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 and a newline to a file descriptor.
ft_putnbr_fd	Writes an integer to a file descriptor.
ft_putbits_fd	Writes the binary representation of a character to a file descriptor.

Part 3 - Linked lists

The lists use this structure, declared in libft.h:

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

Function	What it does
ft_lstnew	Creates a new node.
ft_lstadd_front	Adds a node at the start of the list.
ft_lstadd_back	Adds a node at the end of the list.
ft_lstsize	Counts the nodes in the list.
ft_lstlast	Returns the last node.
ft_lstdelone	Frees one node and its content.
ft_lstclear	Frees a node and all the ones after it.
ft_lstiter	Applies a function to the content of each node.
ft_lstmap	Builds a new list from the results of a function.

Technical choices

• No global variables.
• Helper functions are static.
• Every allocation is checked.
• Memory is freed if something fails.

Resources

References

• man pages of the reimplemented functions (man 3 strlen, etc.)
• Free manual: http://manpagesfr.free.fr/

Use of AI

Minimal use of artificial intelligence for sentence structuring in the README, and for some main.