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*This project has been created as part of the 42 curriculum by tvanbesi*
# Libft
## Description
Libft is a C static library that reimplements a selection of standard C library
functions, along with additional utility functions not found in libc. The goal
is to understand how these foundational functions work internally by coding them
from scratch, and to produce a reusable library for future 42 projects.
The library is organized in three parts:
- **Part 1** — Reimplementations of common libc functions (`strlen`, `memcpy`,
`atoi`, `calloc`, etc.), including several BSD extensions (`strlcpy`,
`strlcat`, `strnstr`).
- **Part 2** — Additional utility functions for string manipulation (`split`,
`substr`, `strjoin`, `strtrim`, `itoa`), higher-order string operations
(`strmapi`, `striteri`), and file-descriptor output (`putchar_fd`,
`putstr_fd`, `putendl_fd`, `putnbr_fd`).
- **Part 3** — A singly-linked list implementation with creation, insertion,
deletion, iteration, and mapping operations.
All functions are prefixed with `ft_` and exposed through a single header,
`libft.h`.
## Instructions
### Requirements
- A C compiler (the Makefile uses `cc`)
- `make`
- `ar` (for building the static archive)
- [`jq`](https://jqlang.github.io/jq/) (only needed for `compile_commands.json` generation)
### Building the library
```sh
make # compiles lib/libft.a
```
### Using the library in your project
1. Copy or link the `src/`, `inc/`, and `Makefile` into your project tree.
2. Include the header in your source files:
```c
#include "libft.h"
```
3. Compile and link against the archive:
```sh
cc -Wall -Wextra -Werror -I inc my_program.c -L lib -lft -o my_program
```
### Makefile targets
| Target | Description |
|-------------------------|------------------------------------------------------|
| `make` / `make all` | Build `lib/libft.a` |
| `make clean` | Remove object files |
| `make fclean` | Remove object files and the library archive |
| `make re` | Full rebuild (`fclean` + `all`) |
| `make test` | Build the library then compile and run all tests |
| `make sanitize` | Rebuild with AddressSanitizer and run tests |
| `make compile_commands.json` | Generate `compile_commands.json` for clangd |
### clangd support
To enable editor features like autocompletion and diagnostics via
[clangd](https://clangd.llvm.org/), generate the compilation database:
```sh
make compile_commands.json # for library sources
make -C tests compile_commands.json # for test sources
```
This requires `jq` to be installed. Regenerate after adding or removing source
files.
### Running the tests
```sh
make test
```
Each test binary compares the `ft_` function against its libc counterpart
(where one exists) using both edge-case and randomized inputs. NULL-pointer
crash behavior is verified via `fork()` + `WIFSIGNALED()`.
## Function reference
### Character classification & conversion
| Function | Description |
|----------------|----------------------------------------------|
| `ft_isalpha` | Check for an alphabetic character |
| `ft_isdigit` | Check for a decimal digit |
| `ft_isalnum` | Check for an alphanumeric character |
| `ft_isascii` | Check for a 7-bit ASCII character |
| `ft_isprint` | Check for a printable character |
| `ft_toupper` | Convert lowercase to uppercase |
| `ft_tolower` | Convert uppercase to lowercase |
### String examination
| Function | Description |
|----------------|------------------------------------------------------|
| `ft_strlen` | Return the length of a string |
| `ft_strncmp` | Compare two strings up to *n* bytes |
| `ft_strchr` | Locate first occurrence of a character in a string |
| `ft_strrchr` | Locate last occurrence of a character in a string |
| `ft_strnstr` | Locate a substring within a bounded region (BSD) |
| `ft_atoi` | Convert a string to an integer |
### String manipulation
| Function | Description |
|----------------|------------------------------------------------------|
| `ft_strlcpy` | Size-bounded string copy (BSD) |
| `ft_strlcat` | Size-bounded string concatenation (BSD) |
| `ft_strdup` | Duplicate a string with `malloc` |
| `ft_substr` | Extract a substring |
| `ft_strjoin` | Concatenate two strings into a new allocation |
| `ft_strtrim` | Trim characters from both ends of a string |
| `ft_split` | Split a string by a delimiter into an array |
| `ft_itoa` | Convert an integer to its decimal string |
| `ft_strmapi` | Apply a function to each character, returning a new string |
| `ft_striteri` | Apply a function to each character in place |
### Memory operations
| Function | Description |
|----------------|----------------------------------------------|
| `ft_memset` | Fill memory with a constant byte |
| `ft_bzero` | Zero a byte range |
| `ft_memcpy` | Copy memory (non-overlapping) |
| `ft_memmove` | Copy memory (overlap-safe) |
| `ft_memchr` | Scan memory for a byte |
| `ft_memcmp` | Compare two memory regions |
| `ft_calloc` | Allocate zeroed memory |
### File descriptor output
| Function | Description |
|------------------|--------------------------------------------|
| `ft_putchar_fd` | Write a character to a file descriptor |
| `ft_putstr_fd` | Write a string to a file descriptor |
| `ft_putendl_fd` | Write a string followed by a newline |
| `ft_putnbr_fd` | Write an integer in decimal |
### Linked list
The list node type is:
```c
typedef struct s_list
{
void *content;
struct s_list *next;
} t_list;
```
| Function | Description |
|-------------------|---------------------------------------------------|
| `ft_lstnew` | Create a new node |
| `ft_lstadd_front` | Insert a node at the beginning |
| `ft_lstadd_back` | Insert a node at the end |
| `ft_lstsize` | Count the nodes in the list |
| `ft_lstlast` | Return the last node |
| `ft_lstdelone` | Delete a single node |
| `ft_lstclear` | Delete and free an entire list |
| `ft_lstiter` | Apply a function to each node's content |
| `ft_lstmap` | Map a function over a list, producing a new list |
## Resources
- [The C Programming Language](https://en.wikipedia.org/wiki/The_C_Programming_Language) (Kernighan & Ritchie) — the classic reference for C
- [C Standard Library reference (cppreference.com)](https://en.cppreference.com/w/c) — detailed documentation for every standard library function
- Linux man pages (`man 3 strlen`, `man 3 memcpy`, etc.) — authoritative per-function documentation
- [OpenBSD `strlcpy`/`strlcat` paper](https://www.sudo.ws/todd/papers/strlcpy.html) — rationale and specification for the BSD string extensions
### Use of AI
AI (Claude) was used in this project for three purposes:
- **Code comments**: generating and reviewing Doxygen-style documentation
comments in the header and source files.
- **Git commit messages**: drafting commit messages.
- **This README**: drafting and structuring the content of this file.
All library code was written by the project author.
|
