CEcole 42ProgrammingProjects

Libft – my own first C library

“Libft – your own first library” is an individual project at 42, it is the second one i have worked on after the “Piscine Reloaded one”.

The aim of this project is to code a C library regrouping usual functions that we’ll be allowed to use in all our other projects. At 42 we are not allowed to use standard C library function, we can use only function we coded ourself. So the longer term goal of this library is to grow with our own function.

For this library there are only 3 standard library function allowed are write() from <unistd.h>, malloc() and free() from <stdlib.h>. We are allowed also to use <string.h> for accessing size_t and NULL.

Here is the link to the GitHub repository: https://github.com/nmanzini/libft-42

LIBFT is the second project we worked on after starting the school. This project required a lot of checking for all the possible cases in which a standard function can fail or not. This library has been thoroughly checked.

Lib C Functions 42 Functions List Functions
memset ft_memalloc ft_lstnew
bzero ft_memdel ft_lstdelone
memcpy ft_strnew ft_lstdel
memccpy ft_strdel ft_lstadd
memmove ft_strclr ft_lstiter
memchr ft_striter ft_lstmap
memcmp ft_striteri
strlen ft_strmap
strdup ft_strmapi
strcpy ft_strequ
strncpy ft_strnequ
strcat ft_strsub
strlcat ft_strjoin
strchr ft_strtrim
strrchr ft_strsplit
strstr ft_itoa
strnstr ft_putchar
strcmp ft_putstr
strncmp ft_putendl
atoi ft_putnbr
isalpha ft_putchar_fd
isdigit ft_putstr_fd
isalnum ft_putendl_fd
isascii ft_putnbr_fd


There are 3 kinds of function:

  • Lib C Functions: are the function coming from standard C libraries have a “ft_” before them to avoid conflict with the original ones.
  • 42 Functions: Functions used at Ecole 42, mainly memory and string manipulation
  • List Functions: Used for list creation and manipulation.

Recreating all these function is a great exercise to understand what these function do in detail, their limitation and unexpected results. Unit testing them is a even greater challenge than writing them.

At 42 we don’t have to study what a function does, when you are stuck for hours recoding them you are forced to understand them deeply.