Libft

A custom C library implementation - 42 School Project

Overview

Libft is the first project at 42 School, where students recreate essential functions from the C standard library along with additional utility functions. This library serves as a foundation for future C projects at 42, providing a personal toolkit of reliable, well-tested functions.

Description

This project involves recoding a set of standard C library functions (from libc) as well as other utility functions that will be useful throughout the cursus. The library is compiled into a static library libft.a that can be linked with other C projects.

Features

Part 1: Libc Functions

Standard C library functions reimplemented with the ft_ prefix:

Character Classification & Conversion:

• ft_isalpha - Check if character is alphabetic
• ft_isdigit - Check if character is a digit
• ft_isalnum - Check if character is alphanumeric
• ft_isascii - Check if character is ASCII
• ft_isprint - Check if character is printable
• ft_toupper - Convert character to uppercase
• ft_tolower - Convert character to lowercase

String Manipulation:

• ft_strlen - Calculate string length
• ft_strlcpy - Size-bounded string copy
• ft_strlcat - Size-bounded string concatenation
• ft_strchr - Locate first occurrence of character
• ft_strrchr - Locate last occurrence of character
• ft_strncmp - Compare strings up to n bytes
• ft_strnstr - Locate substring in string
• ft_strdup - Duplicate string

Memory Functions:

• ft_memset - Fill memory with constant byte
• ft_bzero - Zero out memory
• ft_memcpy - Copy memory area
• ft_memmove - Copy memory area (handles overlap)
• ft_memchr - Scan memory for character
• ft_memcmp - Compare memory areas
• ft_calloc - Allocate and zero memory

Conversion:

• ft_atoi - Convert string to integer

Part 2: Additional Functions

Custom utility functions for string manipulation:

• ft_substr - Extract substring from string
• ft_strjoin - Concatenate two strings
• ft_strtrim - Trim characters from beginning and end
• ft_split - Split string by delimiter
• ft_itoa - Convert integer to string
• ft_strmapi - Apply function to each character (with index)
• ft_striteri - Iterate and apply function to each character

File Descriptor Output:

• ft_putchar_fd - Output character to file descriptor
• ft_putstr_fd - Output string to file descriptor
• ft_putendl_fd - Output string with newline to file descriptor
• ft_putnbr_fd - Output number to file descriptor

Bonus Part: Linked List Functions

Functions for manipulating linked lists using the t_list structure:

• ft_lstnew - Create new list element
• ft_lstadd_front - Add element at beginning of list
• ft_lstadd_back - Add element at end of list
• ft_lstsize - Count elements in list
• ft_lstlast - Get last element of list
• ft_lstdelone - Delete single element
• ft_lstclear - Delete and free list
• ft_lstiter - Iterate and apply function to each element
• ft_lstmap - Iterate and apply function, create new list

Installation & Compilation

Requirements

• GCC compiler
• Make

Compilation

To compile the mandatory part:

make

To compile with bonus functions:

make bonus

This will create the static library libft.a.

Cleaning

Remove object files:

make clean

Remove object files and the library:

make fclean

Recompile everything:

make re

Usage

1. Compile the library:

make

2. Include the header in your C file:

#include "libft.h"

3. Compile your program with the library:

gcc your_program.c libft.a -o your_program

Example

#include "libft.h"
#include <stdio.h>

int main(void)
{
    char *str = "Hello, 42!";
    char *dup;

    dup = ft_strdup(str);
    ft_putendl_fd(dup, 1);
    free(dup);

    return (0);
}

Technical Details

• Language: C
• Compiler: GCC
• Compilation Flags: -Wall -Wextra -Werror
• Norm: 42 School coding standard (Norminette)
• Forbidden:
  • Global variables
  • Using functions not allowed in the subject

Project Structure

libft/
├── Makefile          # Build configuration
├── libft.h           # Header file with function prototypes
├── ft_*.c            # Implementation files (45+ functions)
└── README.md         # This file

About 42 School

This project is part of the 42 School curriculum. 42 is a coding school with a peer-to-peer learning approach and project-based curriculum.

Author

bmetehri - 42 Student

Project completed: January 2023