This project has been created as part of the 42 curriculum by mobouifr.

LIBFT

A foundational C static library that reimplements core libc behaviors and essential string/memory helpers.

What Is This?

libft is a custom static library (libft.a) containing reimplemented libc-style utilities and additional helper functions used throughout the 42 curriculum.

This repository includes character checks, memory functions, string utilities, conversion helpers, dynamic string constructors, split/trim helpers, and file-descriptor output functions. Everything is organized as ft_*.c files with declarations in libft.h.

Technically, it is interesting because it forces precise handling of pointer arithmetic, allocation patterns, boundary conditions, and API behavior compatibility with familiar C functions.

Build your own standard tools first, then build everything else on top of them.

How It Works

The project compiles each source file to an object (.o) with cc -Wall -Werror -Wextra, then archives changed objects into libft.a using ar -rc.

ft_*.c  --(cc -c)-->  ft_*.o  --(ar -rc)-->  libft.a

At code level, many higher-level functions are layered on core helpers already present in the library (for example: ft_strtrim uses ft_strlen, ft_strchr, and ft_strdup; ft_strjoin uses ft_strdup for null-side fallback).

Features

Feature	Status	Notes
Libc-style reimplementations (part 1 set)	✓	Present as dedicated ft_*.c files and declared in libft.h.
Additional string/allocation/output helpers (part 2 set)	✓	All listed part-2 source files are present and compile into the archive.
Static library archive generation	✓	ar -rc produces libft.a from compiled object files.
Bonus linked-list API	—	No *_bonus.c/*_bonus.h files in repository.

Verified function-by-function status

Function	Status	Notes
ft_isalpha	✓	ASCII letter range checks, returns 1/0.
ft_isdigit	✓	ASCII digit range checks, returns 1/0.
ft_isalnum	✓	Combines alpha and digit checks, returns 1/0.
ft_isascii	✓	Checks 0..127, returns 1/0.
ft_isprint	✓	Checks printable ASCII 32..126, returns 1/0.
ft_strlen	✓	Counts bytes until \0.
ft_memset	✓	Byte fill loop over len.
ft_bzero	✓	Zeroes n bytes via byte loop.
ft_memcpy	✓	Copies forward; explicit NULL/NULL guard and same-pointer early return.
ft_memmove	✓	Handles overlap with backward copy when needed.
ft_strlcpy	✓	Copies up to dstsize - 1, always null-terminates when dstsize > 0.
ft_strlcat	✓	Appends into remaining buffer space, returns attempted total length.
ft_toupper	✓	Lowercase ASCII to uppercase.
ft_tolower	✓	Uppercase ASCII to lowercase.
ft_strchr	✓	Finds first match including search for terminating \0.
ft_strrchr	✓	Walks from end to find last occurrence.
ft_strncmp	✓	Byte comparison up to n.
ft_memchr	✓	Scans memory for byte match within n.
ft_memcmp	✓	Bytewise memory comparison.
ft_strnstr	✓	Bounded substring search, includes needle == "" handling.
ft_atoi	✓	Trims ASCII whitespace, parses sign and digits.
ft_calloc	partial	Allocates and zeroes, but overflow check uses 0xffffffff threshold.
ft_strdup	✓	Allocates and copies full C-string.
ft_substr	partial	Handles start >= strlen with empty duplicate; contains dead trailing return (0);.
ft_strjoin	✓	Concatenates strings; also supports single-null fallback via ft_strdup.
ft_strtrim	✓	Trims start/end chars contained in set.
ft_split	✓	Allocates token array, per-token allocation, cleanup-on-failure helper.
ft_itoa	✓	Handles positive/negative conversion and writes digits into allocated output string.
ft_strmapi	✓	Allocates mapped string from callback (index, char).
ft_striteri	✓	In-place callback application with null checks.
ft_putchar_fd	✓	Writes one char when fd != -1.
ft_putstr_fd	✓	Writes full string when s != NULL and fd != -1.
ft_putendl_fd	✓	ft_putstr_fd-style write plus newline.
ft_putnbr_fd	✓	Handles 0, INT_MIN, negatives, and digit emission via local buffer.

Project Structure

.
├── .git/ ← Git metadata directory
├── Makefile ← Build rules for objects and libft.a
├── README.md ← Project documentation
├── libft.h ← Public header with all function prototypes and includes
├── ft_atoi.c ← ASCII-to-int conversion
├── ft_bzero.c ← Zero memory bytes
├── ft_calloc.c ← Allocate + zero-initialize memory
├── ft_isalnum.c ← Alphanumeric classification
├── ft_isalpha.c ← Alphabetic classification
├── ft_isascii.c ← ASCII-range classification
├── ft_isdigit.c ← Digit classification
├── ft_isprint.c ← Printable-character classification
├── ft_itoa.c ← Int-to-string conversion
├── ft_memchr.c ← Search byte in memory region
├── ft_memcmp.c ← Compare memory regions
├── ft_memcpy.c ← Copy memory (non-overlap style)
├── ft_memmove.c ← Copy memory with overlap safety
├── ft_memset.c ← Fill memory with a byte
├── ft_putchar_fd.c ← Write one char to a file descriptor
├── ft_putendl_fd.c ← Write string + newline to a file descriptor
├── ft_putnbr_fd.c ← Write integer to a file descriptor
├── ft_putstr_fd.c ← Write string to a file descriptor
├── ft_split.c ← Split string by delimiter into allocated array
├── ft_strchr.c ← Find first character occurrence
├── ft_strdup.c ← Duplicate string to new allocation
├── ft_striteri.c ← In-place per-char iteration callback
├── ft_strjoin.c ← Concatenate two strings into new allocation
├── ft_strlcat.c ← Size-bounded append
├── ft_strlcpy.c ← Size-bounded copy
├── ft_strlen.c ← String length
├── ft_strmapi.c ← Mapped copy via callback
├── ft_strncmp.c ← Compare two strings up to n bytes
├── ft_strnstr.c ← Bounded substring search
├── ft_strrchr.c ← Find last character occurrence
├── ft_strtrim.c ← Trim character set from both ends
├── ft_substr.c ← Extract substring into new allocation
├── ft_tolower.c ← Upper-to-lower ASCII conversion
└── ft_toupper.c ← Lower-to-upper ASCII conversion

Getting Started

Build Commands (verified in this repository)

make fclean
make

Makefile Rules

Rule	Verified behavior
all	Triggers $(NAME) build path.
$(NAME)	Runs ar -rc libft.a $? after object compilation.
clean	Removes object files listed in $(OBJ).
fclean	Runs clean then removes libft.a.
re	Runs fclean then all.

Build Configuration

Key	Value
Compiler	cc
Flags	-Wall -Werror -Wextra
Archive tool	ar -rc
Output	libft.a

Resources

Resource	Why it matters here
42 Libft subject (v19.2)	Defines expected function set and constraints for this project.
man pages for libc functions	Baseline behavior references for reimplementations.
GNU Make manual	Useful for understanding pattern rules (.c.o) and rebuild logic.