Libft

Welcome to my implementation of Libft, a foundational project at 42 that re-creates many functions from the C standard library. This project was a great opportunity to improve my understanding of memory management, string manipulation, and function implementation in C.

🚀 Project Overview

The goal of this project was to code a custom standard library in C, including:

• Standard functions like memcpy, strlen, strdup, etc.
• String, memory, and character operations
• Custom utility functions to extend functionality

Note: This version does not include the bonus part (linked list operations).

This library can be reused in future C projects at 42 or anywhere a custom lightweight utility library is needed.

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🧠 What I Learned

• Deep understanding of memory allocation and pointer arithmetic in C
• Efficient handling of strings, arrays, and memory blocks
• Structuring reusable C code
• Writing a complete Makefile and header file
• Defensive programming and error handling

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📁 Project Structure

libft/
├── ft_*.c            # All custom standard C functions
├── libft.h           # Function declarations
├── Makefile          # Project build rules

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🛠️ Functions Implemented

✅ Libc Functions (Part 1)

• ft_isalpha: Checks if a character is an alphabetic letter (A-Z or a-z).
• ft_isdigit: Checks if a character is a digit (0-9).
• ft_isalnum: Checks if a character is alphanumeric (letter or digit).
• ft_isascii: Checks if a character is an ASCII character (0–127).
• ft_isprint: Checks if a character is printable, including space.
• ft_strlen: Returns the length of a string (excluding the null terminator).
• ft_memset: Fills a block of memory with a specified byte.
• ft_bzero: Sets a block of memory to zero bytes.
• ft_memcpy: Copies a block of memory from source to destination.
• ft_memmove: Copies memory safely, handling overlapping regions.
• ft_strlcpy: Copies a string to a buffer of a given size, ensuring null-termination.
• ft_strlcat: Appends a string to another, with buffer size checks.
• ft_toupper: Converts a lowercase letter to uppercase.
• ft_tolower: Converts an uppercase letter to lowercase.
• ft_strchr: Returns a pointer to the first occurrence of a character in a string.
• ft_strrchr: Returns a pointer to the last occurrence of a character in a string.
• ft_strncmp: Compares two strings up to a given number of characters.
• ft_memchr: Scans memory for a specific byte.
• ft_memcmp: Compares two blocks of memory.
• ft_strnstr: Locates a substring in a string, searching up to a given length.
• ft_atoi: Converts a string to an integer.
• ft_calloc: Allocates and zeros memory for an array.
• ft_strdup: Duplicates a string by allocating new memory.

✅ Additional Functions (Part 2)

• ft_substr: Extracts a substring from a string, given start index and length.
• ft_strjoin: Concatenates two strings into a newly allocated string.
• ft_strtrim: Trims characters from the start and end of a string.
• ft_split: Splits a string into an array of strings using a delimiter.
• ft_itoa: Converts an integer to its string representation.
• ft_strmapi: Applies a function to each character of a string to create a new string.
• ft_striteri: Applies a function to each character of a string, modifying it in place.
• ft_putchar_fd: Writes a character to a given file descriptor.
• ft_putstr_fd: Writes a string to a given file descriptor.
• ft_putendl_fd: Writes a string followed by a newline to a file descriptor.
• ft_putnbr_fd: Writes an integer to a given file descriptor.

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🧪 How to Use

1. Clone the repository:

git clone https://github.com/your-username/libft.git
cd libft

2. Build the library:

make

This will compile all .c files and create libft.a.

3. Use in your C project:

In your source code:

#include "libft.h"

To compile:

gcc -Wall -Wextra -Werror your_code.c -L. -lft

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🧪 Test Your Implementation

You can test your libft implementation using Francinette, a popular automated testing tool designed for 42 libft projects.

To use Francinette:

1. Clone the repo:

   git clone https://github.com/alelievr/francinette.git

2. Follow the instructions in its README to set up and run tests.

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🧾 License

This project is part of the 42 School curriculum. You’re welcome to use and learn from it, but do not copy it directly for your own submission.

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👤 Author

Hossein Khoshnevis
🧠 Software Developer | 📍 Based in the Netherlands
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