Libft: Building Your Own C Library

This project is one of the first practical steps into low-level programming: building your own library of functions in C, just like in the 42Madrid cursus. The goal isn’t just to copy libc functions, but to understand how they work, replicate them, and learn good programming and memory management practices.

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🌐 What’s Libft about?

Libft consists of programming basic functions that will serve as the foundation for future projects in the cursus. It’s a great opportunity to:

• Get familiar with pointers and memory management
• Learn to modularize code
• Practice compilation and creation of static libraries (libft.a)
• Understand how standard C functions are built under the hood

In short, Libft is your personal toolbox in C.

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🧩Project Objective

• Build a C library with general-purpose functions.
• Functions should replicate libc behavior or complement it with useful string and memory utilities.
• Code must be modular, clean, and comply with 42’s compilation standards (-Wall -Werror -Wextra).
• No global variables allowed; any helper function must be declared static in its file.

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⚙️Technical Considerations

• Libtool is forbidden; use the ar command to generate the library.
• Do not submit unnecessary files.
• All functions must follow original libc prototypes, but with the prefix ft_ (e.g., strlen → ft_strlen).

📝Part 1: Replicating libc Functions

In this section, you will recreate standard library functions with your own implementations:

isalpha	toupper
isdigit	tolower
isalnum	strchr
isascii	strrchr
isprint	strncmp
strlen	memchr
memset	memcmp
bzero	strnstr
memcpy	atoi
memmove	calloc
strlcpy	strdup
strlcat

Each function must behave exactly like its original version.

📝Part 2: Additional Functions

Here you will develop functions that are not in libc or behave differently, useful for string and number manipulation:

ft_substr	ft_strjoin
ft_strtrim	ft_split
ft_itoa	ft_strmapi
ft_striteri	ft_putchar_fd
ft_putstr_fd	ft_putendl_fd
ft_putnbr_fd

These functions teach you to manage memory dynamically, manipulate strings, and write utilities that make your code more modular.

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🌟Bonus: Linked Lists

Once you master strings and memory, it’s time to move on to linked lists:

typedef struct s_list
{
   void *content;

   struct s_list *next;

} t_list;

• content: stores any type of information (void*)
• next: points to the next node or NULL if it’s the last one

Functions to implement for easy list management:

ft_lstnew	ft_lstadd_front
ft_lstsize	ft_lstlast
ft_lstadd_back	ft_lstdelone
ft_lstclear	ft_lstiter
ft_lstmap

Learning lists is key for more complex data structures you’ll encounter later.

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🚀Project and Submission

• A Makefile is provided to compile the static library libft.a
• Includes all functions developed in the project
• Project fulfills all requirements of the 42Madrid cursus

⚠️Important 

This project was adapted and reorganized: since it is a library, I modified its structure by separating the functions into categories for better organization. Additionally, I incorporated the Get_next_line and Ft_printf functions —two additional projects from the 42Madrid curriculum— with the goal of making the library easier to use and more convenient to integrate into future projects.

🧩Compile Options:

$ make
The **make** rule will compile the whole library generating a static library 'libft.a' containing all the functions of the project.
$ make clean
The **clean** rule will delete all objects created to compile the library 'libft.a'.
$ make fclean
The **fclean** rule will delete all created objects and the 'libft.a' file that has been previously compiled.
$ make re
The **re** rule will remove all compiled objects and files (if any) and recompile the library.

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🏁Conclusion

Libft is much more than just a C exercise. It teaches you to:

• Understand how the standard library works
• Handle memory and pointers responsibly
• Modularize and structure code
• Build your own reusable toolbox

Perfect for consolidating C programming fundamentals before moving on to more complex projects at 42Madrid 😄