Libft

The Libft project at 42 is designed to introduce students to the concept of building their own C standard library. This project requires implementing a set of essential functions from <string.h>, <stdlib.h>, and other standard C libraries, allowing students to gain a deep understanding of memory management, string manipulation, and linked list operations.

Libft is a foundational project that challenges students to write and optimize their own versions of common C library functions. The goal is to create a reusable library that can be used in future projects at 42.

The project covers:

• Memory manipulation functions (e.g., memset, bzero, memcpy, memmove, calloc, realloc)

• String manipulation functions (e.g., strlen, strdup, strjoin, strtrim)

• Character classification functions (e.g., isdigit, isalpha, toupper, tolower)

• Linked list operations (e.g., lstnew, lstadd_front, lstadd_back, lstsize, lstdelone)

• Implement a static library called libft.a containing the required functions.

• Functions must match their standard library counterparts in behavior and return values.

• Memory allocation functions must properly handle errors.

• Implement additional utility functions to extend the library’s functionality.

• No use of external libraries or unauthorized functions.

• Implement additional linked list functions such as:

  • ft_lstmap() - Applies a function to each node of a linked list.

  • ft_lstiter() - Iterates through a linked list.

• Implement functions to handle more complex string operations.

• ft_memset(void *s, int c, size_t n): Fills n bytes of memory with the specified byte c.

• ft_bzero(void *s, size_t n): Sets n bytes of memory to zero.

• ft_memcpy(void *dest, const void *src, size_t n): Copies n bytes from src to dest.

• ft_memmove(void *dest, const void *src, size_t n): Copies n bytes, handling overlapping memory regions.

• ft_strlen(const char *s): Returns the length of a string.

• ft_strcpy(char *dest, const char *src): Copies src into dest.

• ft_strcat(char *dest, const char *src): Appends src to dest.

• ft_strjoin(const char *s1, const char *s2): Concatenates two strings and returns a new string.

• ft_isalpha(int c): Checks if a character is an alphabetic letter.

• ft_isdigit(int c): Checks if a character is a digit.

• ft_isalnum(int c): Checks if a character is alphanumeric.

• ft_tolower(int c): Converts an uppercase letter to lowercase.

• ft_toupper(int c): Converts a lowercase letter to uppercase.

• ft_lstnew(void *content): Creates a new list node with the given content.

• ft_lstadd_front(t_list **lst, t_list *new): Adds a new node at the beginning of the list.

• ft_lstadd_back(t_list **lst, t_list *new): Adds a new node at the end of the list.

• ft_lstsize(t_list *lst): Returns the number of nodes in a list.

• ft_lstclear(t_list **lst, void (*del)(void *)): Deletes and frees the entire list.

To use libft.a in another project, include the header file:

#include "libft.h"

To compile the library, run:

make

To clean object files:

make clean

To remove all compiled files:

make fclean

To recompile everything:

make re

$\color{crimson}{\textbf{Memory Leaks}}$: Always ensure that dynamically allocated memory is properly freed.

$\color{crimson}{\textbf{Undefined Behavior}}$: Pay attention to buffer overflows and null pointer dereferencing.

$\color{crimson}{\textbf{Function Matching}}$: Make sure each function behaves exactly like its standard library equivalent.

$\color{crimson}{\textbf{Makefile Errors}}$: Ensure that make clean, make fclean, and make re work correctly.

The $\color{RoyalBlue}{\textbf{Libft}}$ project is a foundational part of the 42 curriculum, helping students develop a deeper understanding of C programming, memory management, and efficient algorithm implementation. Mastering this project is crucial, as the functions implemented here will be reused in many future projects.