Libft

42 - Implementing our own Library in C

My implementation of some of the Standard C Library functions including some additional ones.

Table Of Contents

• What is libft?
• What's in it?
• How does it work?
• Usage

What is libft?

Libft (see PDF) is an individual project at 42 that requires us to re-create some standard C library functions including some additional ones that can be used later to build a library of useful functions for the rest of the curriculum.

Disclaimer: Reinventing the wheel is not something we do for fun. 42 makes us do this just so we can have a deeper understanding of data structures and basic algorithms. At 42 we're not allowed to use standard libraries on our projects, so we have to keep growing this library with our own functions as we go further in the curriculum.

What's in it?

I separated my lib into 6 different categories::

1. Strings Functions: All functions manipulating characters and strings
2. Conversion functions: Functions useful to convert numbers to strings or strings to numbers
3. Lists Functions: All functions manipulating lists
4. Memory Functions: Functions related to memory allocation/use/comparison
5. Output Functions: Functions to display/output on the terminal
6. Other Functions: Binary functions, maths functions, get_next_line, ...

Strings Functions	Conversion Functions	Lists Functions	Memory Functions	Output Functions	Other Functions
count_occurence	ft_atoi	ft_islist_sorted	ft_bzero	ft_printf	get_bits
ft_isalnum	ft_binatoi	ft_lstclr	ft_memcpy	ft_putchar	print_bits
ft_isalpha	ft_itoa	ft_lstdelone	ft_memccpy	ft_putendl	swap_bits
ft_isdigit	ft_itoa_base	ft_lstnew	ft_memcmp	ft_putnbr	ft_show_tab
ft_isinteger	ft_llitoa	ft_lstrevrotate	ft_memdel	ft_putstr_fd	ft_sqrt
ft_islower	ft_ullitoa	ft_lst_bubblesort	ft_memset	ft_putnbrendl	get_next_line
ft_isupper	ft_llitoa_base	ft_lstcount	ft_memalloc	ft_putchar_fd	sort_int_tab
ft_isnumeric	ft_ullitoa_base	ft_lstiter	ft_memchr	ft_putendl_fd	ft_max
ft_isprint	ft_atoull	ft_lstprepend	ft_memmove	ft_putnbr_f	ft_power
ft_isupper		ft_lstrotate	ft_realloc	ft_putstr	ft_recursive_power
ft_iswhitespace		ft_lst_mergesort
ft_split_whitespace		ft_lstcpy
ft_str_notchr		ft_lstmap
ft_str_notchr_index		ft_lstpush
ft_strcat		ft_lstswap
ft_strchr		ft_lstappend
ft_strclr		ft_lstdel
ft_strcmp		ft_lstncpy
ft_strcpy		ft_lstrev
ft_strdel
ft_strdup
ft_strequ
ft_striter
ft_striteri
ft_strjoin
ft_strlcat
ft_strlen
ft_strmap
ft_strmapi
ft_strncat
ft_strncmp
ft_strncpy
ft_strnequ
ft_strnew
ft_strnstr
ft_strr_notchr_index
ft_strrchr
ft_strsplit
ft_strstr
ft_strstr_delim
ft_strsub
ft_strtolower
ft_strtoupper
ft_strtrim
ft_tolower
ft_toupper
variadic_strjoin

Notes:

• The project instructions require that we put all the source files in the root directory but for more conveniency, I separate them into sub folders.
• I update this list every now and then with new personal functions. If you don't know what a function does, refer to the man or just test it (or ask me).

How does it work?

The goal is to create a library called libft.a from the source files so we can later use that library from other projects at 42.

To create that library, after downloading/cloning this project, cd into the project, copy all the files from the sub folders to the root directory and finally, call make:

git clone https://github.com/bwan-nan/libft
cd libft
make

You should see a libft.a file and some object files (.o).

make clean

From there, you can basically call any of the functions present in my libft in another program.

Usage example

Here's a basic example: If you create a file named example.c and write the following code:

#include "libft.h"

int main(void)
{
	ft_putstr("Hello world\n");
	return (0);
}

You can then compile it with libft.a using this command:

clang -Wall -Werror -Wextra example.c libft.a -I inc -o example

Finally, running ./example | cat -e should display:

Hello world$

Concrete usage

This is a list of my projects that use Libft extensively:

• lem_in
• push_swap
• ft_ls
• ft_printf
• Fillit
• get_next_line