🧠 Libft — My Own Implementation of libc

42 Barcelona Project — Author: agarcia2

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📖 Description

Libft is the first mandatory project at 42 School.
The goal is to reimplement standard C library functions and build additional utilities from scratch.
This project teaches how to manage memory, strings, and linked lists while understanding low-level behavior in C.

By the end, you will have your own version of libc, reusable in all your future C projects.

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⚙️ Compilation

make            # Compile libft.a
make clean      # Remove object files
make fclean     # Remove object files and libft.a
make re         # Recompile everything from scratch

🧩 Part 1 — Reimplemented libc Functions

Nº	Function	Prototype	Description
1	ft_isalpha	int ft_isalpha(int c);	Checks if c is an alphabetic character.
2	ft_isdigit	int ft_isdigit(int c);	Checks if c is a decimal digit.
3	ft_isalnum	int ft_isalnum(int c);	Checks if c is alphanumeric.
4	ft_isascii	int ft_isascii(int c);	Checks if c belongs to the ASCII table.
5	ft_isprint	int ft_isprint(int c);	Checks if c is printable.
6	ft_strlen	size_t ft_strlen(const char *s);	Returns the length of a string.
7	ft_memset	void *ft_memset(void *b, int c, size_t len);	Fills memory with a constant byte.
8	ft_bzero	void ft_bzero(void *s, size_t n);	Sets memory to zero.
9	ft_memcpy	void *ft_memcpy(void *dst, const void *src, size_t n);	Copies n bytes from src to dst.
10	ft_memmove	void *ft_memmove(void *dst, const void *src, size_t len);	Safely copies memory (handles overlap).
11	ft_strlcpy	size_t ft_strlcpy(char *dst, const char *src, size_t dstsize);	Copies a string with size limit.
12	ft_strlcat	size_t ft_strlcat(char *dst, const char *src, size_t dstsize);	Concatenates strings with size limit.
13	ft_toupper	int ft_toupper(int c);	Converts a character to uppercase.
14	ft_tolower	int ft_tolower(int c);	Converts a character to lowercase.
15	ft_strchr	char *ft_strchr(const char *s, int c);	Locates first occurrence of a character.
16	ft_strrchr	char *ft_strrchr(const char *s, int c);	Locates last occurrence of a character.
17	ft_strncmp	int ft_strncmp(const char *s1, const char *s2, size_t n);	Compares two strings up to n bytes.
18	ft_memchr	void *ft_memchr(const void *s, int c, size_t n);	Searches for a byte in a memory block.
19	ft_memcmp	int ft_memcmp(const void *s1, const void *s2, size_t n);	Compares two memory blocks.
20	ft_strnstr	char *ft_strnstr(const char *haystack, const char *needle, size_t len);	Searches for a substring.
21	ft_atoi	int ft_atoi(const char *str);	Converts a string to an integer.
22	ft_calloc	void *ft_calloc(size_t count, size_t size);	Allocates zero-initialized memory.
23	ft_strdup	char *ft_strdup(const char *s1);	Duplicates a string.

🧮 Part 2 — Additional Utility Functions

Nº	Function	Prototype	Description
24	ft_substr	char *ft_substr(char const *s, unsigned int start, size_t len);	Extracts a substring from a string.
25	ft_strjoin	char *ft_strjoin(char const *s1, char const *s2);	Joins two strings into a new one.
26	ft_strtrim	char *ft_strtrim(char const *s1, char const *set);	Trims specific characters from both ends of a string.
27	ft_split	char **ft_split(char const *s, char c);	Splits a string into an array of words using a delimiter.
28	ft_itoa	char *ft_itoa(int n);	Converts an integer into a string.
29	ft_strmapi	char *ft_strmapi(char const *s, char (*f)(unsigned int, char));	Applies a function to each character (creates a new string).
30	ft_striteri	void ft_striteri(char *s, void (*f)(unsigned int, char*));	Applies a function to each character (in-place).
31	ft_putchar_fd	void ft_putchar_fd(char c, int fd);	Writes a character to a given file descriptor.
32	ft_putstr_fd	void ft_putstr_fd(char *s, int fd);	Writes a string to a given file descriptor.
33	ft_putendl_fd	void ft_putendl_fd(char *s, int fd);	Writes a string followed by a newline.
34	ft_putnbr_fd	void ft_putnbr_fd(int n, int fd);	Writes an integer as characters to a file descriptor.