C programming can be very tedious when one doesn’t have access to those highly useful standard functions. This project makes you to take the time to re-write those functions, understand them, and learn to use them. This library will help you for all your future C projects.
Through this project, we also give you the opportunity to expand the list of functions with your own. Take the time to expand your libft throughout the year.
• You must create the following functions in the order you believe makes most sense. We encourage you to use the functions you have already coded to write the next ones. The difficulty level does not increase by assignment and the project has not been structured in any specific way. It is similar to a video game, where you can complete quests in the order of your choosing and use the loot from the previous quests to solve the next ones.
• Your project must be written in accordance with the Norm.
• Your functions should not quit unexpectedly (segmentation fault, bus error, double free, etc) apart from undefined behaviors. If this happens, your project will be considered non functional and will receive a 0 during the defence.
• All heap allocated memory space must be properly freed when necessary.
• You must submit a file named author containing your username followed by a ’\n’ at the root of your repository,
$>cat -e author
xlogin$
• You must submit a C file for each function you create, as well as a libft.h file, which will contain all the necessary prototypes as well as macros and typedefs you might need. All those files must be at the root of your repository.
• You must submit a Makefile which will compile your source files to a static library libft.a.
• Your Makefile must at least contain the rules $(NAME), all, clean, fclean et re in the order that you will see fit.
• Your Makefile must compile your work with the flags -Wall, -Wextra and -Werror.
• Only the following libc functions are allowed : malloc(3), free(3) and write(2), and their usage is restricted. See below.
• You must include the necessary include system files to use one or more of the three authorized functions in your .c files. The only additional system include file you are allowed to use is string.h to have access to the constant NULL and to the type size_t. Everything else if forbidden.
• We encourage you to create test programs for your library even though this work won’t have to be submitted and won’t be graded. It will give you a chance to easily test your work and your peers’ work. You will find those tests especially useful during your defence. Indeed, during defence, you are free to use your tests and/or the tests of the peer you are evaluating.
V.1 Technical considerations
• Your libft.h file can contain macros and typedefs if needed.
• A string must ALWAYS end with a ’\0’, even if it is not included in the function’s description, unless explicitly stated otherwise.
• It is forbidden to use global variables.
• If you need sub-functions to write a complex function, you must define these sub- functions as static as stipulated in the Norm.
Check out this link to find out more about static functions:
http://codingfreak.blogspot.com/2010/06/static-functions-in-c.html
• You must pay attention to your types and wisely use the casts when needed, es- pecially when a void* type is involved. Generally speaking, avoid implicit casts. Example:
char *str;
str = malloc(42 * sizeof(*str)); /* Wrong ! Malloc returns a void * (implicit cast) */
str = (char *) malloc(42 * sizeof(*str)); /* Right ! (explicit cast) */
In this first part, you must re-code a set of the libc functions, as defined in their man. Your functions will need to present the same prototype and behaviors as the orig- inals. Your functions’ names must be prefixed by “ft_”. For instance strlen becomes ft_strlen.
Some of the functions’ prototypes you have to re-code use the"restrict" qualifier. This keyword is part of the c99 standard.
It is therefore forbidden to include it in your prototypes and to compile it with the flag -std=c99.
You must re-code the following functions:
• memset
• bzero
• memcpy
• memccpy
• memmove
• memchr
• memcmp
• strlen
• strdup
• strcpy
• strncpy
• strcat
• strncat
• strlcat
• strchr
• strrchr
• strstr
• strnstr
• strcmp
• strncmp
• atoi
• isalpha
• isdigit
• isalnum
• isascii
• isprint
• toupper
• tolower
V.3 Part 2 - Additional functions
In this second part, you must code a set of functions that are either not included in the libc, or included in a different form. Some of these functions can be useful to write Part 1’s functions.
•ft_memalloc
Prototype: void * ft_memalloc(size_t size);
Description: Allocates (with malloc(3)) and returns a “fresh” memory area. The memory allocated is initialized to 0. If the alloca- tion fails, the function returns NULL.
Param. #1: The size of the memory that needs to be allocated.
Return value: The allocated memory area.
Libc functions: malloc(3)
•ft_memdel
Prototype: void ft_memdel(void **ap);
Description: Takes as a parameter the address of a memory area that needs to be freed with free(3), then puts the pointer to NULL.
Param. #1: A pointer’s address that needs its memory freed and set to NULL.
Return value: None.
Libc functions: free(3)
•ft_strnew
Prototype: char * ft_strnew(size_t size);
Description: Allocates (with malloc(3)) and returns a “fresh” string end- ing with ’\0’. Each character of the string is initialized at ’\0’. If the allocation fails the function returns NULL.
Param. #1: The size of the string to be allocated.
Return value: The string allocated and initialized to 0.
Libc functions: malloc(3)
•ft_strdel
Prototype: void ft_strdel(char **as);
Description: Takes as a parameter the address of a string that need to be freed with free(3), then sets its pointer to NULL.
Param. #1: The string’s address that needs to be freed and its pointer set to NULL.
Return value: None.
Libc functions: Free(3).
•ft_strclr
Prototype: void ft_strclr(char *s);
Description: Sets every character of the string to the value ’\0’.
Param. #1: The string that needs to be cleared.
Return value: None.
Libc functions: None.
•ft_striter
Prototype: void ft_striter(char *s, void (*f)(char *));
Description: Applies the function f to each character of the string passed as argument. Each character is passed by address to f to be modified if necessary.
Param. #1: The string to iterate.
Param. #2: The function to apply to each character of s.
Return value: None.
Libc functions: None.
•ft_striteri
Prototype: void ft_striteri(char *s, void (*f)(unsigned int, char *));
Description: Applies the function f to each character of the string passed as argument, and passing its index as first argument. Each character is passed by address to f to be modified if necessary.
Param. #1: The string to iterate.
Param. #2: The function to apply to each character of s and its index.
Return value: None.
Libc functions: None.
•ft_strmap
Prototype: char * ft_strmap(char const *s, char (*f)(char));
Description: Applies the function f to each character of the string given as argument to create a “fresh” new string (with malloc(3)) resulting from the successive applications of f.
Param. #1: The string to map.
Param. #2: The function to apply to each character of s.
Return value: The “fresh” string created from the successive applications of f.
Libc functions: malloc(3)
•ft_strmapi
Prototype: char * ft_strmapi(char const *s, char (*f)(unsigned int, char));
Description: Applies the function f to each character of the string passed as argument by giving its index as first argument to create a “fresh” new string (with malloc(3)) resulting from the suc- cessive applications of f.
Param. #1: The string to map.
Param. #2: The function to apply to each character of s and its index.
Return value: The “fresh” string created from the successive applications of f.
Libc functions: malloc(3)
•ft_strequ
Prototype: int ft_strequ(char const *s1, char const *s2);
Description: Lexicographical comparison between s1 and s2. If the 2 strings are identical the function returns 1, or 0 otherwise.
Param. #1: The first string to be compared.
Param. #2: The second string to be compared.
Return value: 1 or 0 according to if the 2 strings are identical or not.
Libc functions: None.
•ft_strnequ
Prototype: int ft_strnequ(char const *s1, char const *s2, size_t n);
Description: Lexicographical comparison between s1 and s2 up to n char- acters or until a ’\0’ is reached. If the 2 strings are identical, the function returns 1, or 0 otherwise.
Param. #1: The first string to be compared.
Param. #2: The second string to be compared.
Param. #3: The maximum number of characters to be compared.
Return value: 1 or 0 according to if the 2 strings are identical or not.
Libc functions: None.
•ft_strsub
Prototype: char * ft_strsub(char const *s, unsigned int start, size_t len);
Description: Allocates (with malloc(3)) and returns a “fresh” substring from the string given as argument. The substring begins at indexstart and is of size len. If start and len aren’t refer- ing to a valid substring, the behavior is undefined. If the allocation fails, the function returns NULL.
Param. #1: The string from which create the substring.
Param. #2: The start index of the substring.
Param. #3: The size of the substring.
Return value: The substring.
Libc functions: malloc(3)
•ft_strjoin
Prototype: char * ft_strjoin(char const *s1, char const *s2);
Description: Allocates (with malloc(3)) and returns a “fresh” string end- ing with ’\0’, result of the concatenation of s1 and s2. If the allocation fails the function returns NULL.
Param. #1: The prefix string.
Param. #2: The suffix string.
Return value: The “fresh” string result of the concatenation of the 2 strings.
Libc functions: malloc(3)
•ft_strtrim
Prototype: char * ft_strtrim(char const *s);
Description: Allocates (with malloc(3)) and returns a copy of the string given as argument without whitespaces at the beginning or at the end of the string. Will be considered as whitespaces the following characters ’ ’, ’\n’ and ’\t’. If s has no whites- paces at the beginning or at the end, the function returns a copy of s. If the allocation fails the function returns NULL.
Param. #1: The string to be trimed.
Return value: The “fresh” trimmed string or a copy of s.
Libc functions: malloc(3)
•ft_strsplit
Prototype: char ** ft_strsplit(char const *s, char c);
Description: Allocates (with malloc(3)) and returns an array of “fresh” strings (all ending with ’\0’, including the array itself) ob- tained by spliting s using the character c as a delimiter. If the allocation fails the function returns NULL. Example : ft_strsplit("*hello*fellow***students*", ’*’) re- turns the array ["hello", "fellow", "students"].
Param. #1: The string to split.
Param. #2: The delimiter character.
Return value: The array of “fresh” strings result of the split.
Libc functions: malloc(3), free(3)
•ft_itoa
Prototype: char * ft_itoa(int n);
Description: Allocate (with malloc(3)) and returns a “fresh” string end- ing with ’\0’ representing the integer n given as argument. Negative numbers must be supported. If the allocation fails, the function returns NULL.
Param. #1: The integer to be transformed into a string.
Return value: The string representing the integer passed as argument.
Libc functions: malloc(3)
•ft_putchar
Prototype: void ft_putchar(char c);
Description: Outputs the character c to the standard output.
Param. #1: The character to output.
Return value: None.
Libc functions: write(2).
•ft_putstr
Prototype: void ft_putstr(char const *s);
Description: Outputs the string s to the standard output.
Param. #1: The string to output.
Return value: None.
Libc functions: write(2).
•ft_putendl
Prototype: void ft_putendl(char const *s);
Description: Outputs the string s to the standard output followed by a ’\n’.
Param. #1: The string to output.
Return value: None.
Libc functions: write(2).
•ft_putnbr
Prototype: void ft_putnbr(int n);
Description: Outputs the integer n to the standard output.
Param. #1: The integer to output.
Return value: None.
Libc functions: write(2).
•ft_putchar_fd
Prototype: void ft_putchar_fd(char c, int fd);
Description: Outputs the char c to the file descriptor fd.
Param. #1: The character to output.
Param. #2: The file descriptor.
Return value: None.
Libc functions: write(2).
•ft_putstr_fd
Prototype: void ft_putstr_fd(char const *s, int fd);
Description: Outputs the string s to the file descriptor fd.
Param. #1: The string to output.
Param. #2: The file descriptor.
Return value: None.
Libc functions: write(2).
•ft_putendl_fd
Prototype: void ft_putendl_fd(char const *s, int fd);
Description: Outputs the string s to the file descriptor fd followed by a ’\n’.
Param. #1: The string to output.
Param. #2: The file descriptor.
Return value: None.
Libc functions: write(2).
•ft_putnbr_fd
Prototype: void ft_putnbr_fd(int n, int fd);
Description: Outputs the integer n to the file descriptor fd.
Param. #1: The integer to print.
Param. #2: The file descriptor.
Return value: None.
Libc functions: write(2).
If you successfully completed the mandatory part, you’ll enjoy taking it further. You can see this last section as Bonus Points.
Having functions to manipulate memory and strings is very useful, but you’ll soon discover that having functions to manipulate lists is even more useful.
You’ll use the following structure to represent the links of your list. This structure must be added to your libft.h file.
typedef struct s_list
{
void *content;
size_t content_size;
struct s_list *next;
} t_list;
Here is a description of the fields of the t_list struct:
• content : The data contained in the link. The void * allows to store any kind of
data.
• content_size : The size of the data stored. The void * type doesn’t allow you to know the size of the pointed data, as a consequence, it is necessary to save its size. For instance, the size of the string "42" is 3 bytes and the 32bits integer 42 has a size of 4 bytes.
• next : The next link’s address or NULL if it’s the last link.
The following functions will allow you to manipulate your lists more easilly.
•ft_lstnew
Prototype: t_list * ft_lstnew(void const *content, size_t content_size);
Description: Allocates (with malloc(3)) and returns a “fresh” link. The variables content and content_size of the new link are ini- tialized by copy of the parameter: of the function. If the pa- rameter content is nul, the variable content is initialized to NULL and the variable content_size is initialized to 0 even if the parameter: content_size isn’t. The variable next is initialized to NULL. If the allocation fails, the function returns NULL.
Param. #1: The content to put in the new link.
Param. #2: The size of the content of the new link.
Return value: The new link.
Libc functions: malloc(3), free(3)
•ft_lstdelone
Prototype: void ft_lstdelone(t_list **alst, void (*del)(void *, size_t));
Description: Takes as a parameter: a link’s pointer address and frees the memory of the link’s content using the function del given as a parameter: then frees the link’s memory using free(3). The memory of next must not be freed under any circumstance. Finally, the pointer to the link that was just freed must be set to NULL (quite similar to the function ft_memdel in the mandatory part).
Param. #1: The adress of a pointer to a link that needs to be freed.
Return value: None.
Libc functions: free(3)
•ft_lstdel
Prototype: void ft_lstdel(t_list **alst, void (*del)(void *, size_t));
Description: Takes as a parameter: the adress of a pointer to a link and frees the memory of this link and every successors of that link using the functions del and free(3). Finally the pointer to the link that was just freed must be set to NULL (quite similar to the function ft_memdel from the mandatory part).
Param. #1: The address of a pointer to the first link of a list that needs to be freed.
Return value: None.
Libc functions: free(3)
•ft_lstadd
Prototype: void ft_lstadd(t_list **alst, t_list *new);
Description: Adds the element new at the beginning of the list.
Param. #1: The address of a pointer to the first link of a list.
Param. #2: The link to add at the beginning of the list.
Return value: None.
Libc functions: None.
•ft_lstiter
Prototype: void ft_lstiter(t_list *lst, void (*f)(t_list *elem));
Description: Iterates the list lst and applies the function f to each link.
Param. #1: A pointer to the first link of a list.
Param. #2: The address of a function to apply to each link of a list.
Return value: None.
Libc functions: None.
•ft_lstmap
Prototype: t_list * ft_lstmap(t_list *lst, t_list * (*f)(t_list *elem));
Description: Iterates a list lst and applies the function f to each link to create a “fresh” list (using malloc(3)) resulting from the suc- cessive applications of f. If the allocation fails, the function returns NULL.
Param. #1: A pointer’s to the first link of a list.
Param. #2: The address of a function to apply to each link of a list.
Return value: The new list.
Libc functions: malloc(3), free(3).
Submit your work on your GiT repository as usual. Only the work on your repository will be graded.
Once your have completed your defences, Deepthought (the “moulinette”) will grade your work. Your final grade will be calculated taking into account your peer-correction grades and Deepthought’s grade.
Deepthought will grade your assignments in the order of the subject : Part 1, Part 2 and Bonus. One error in one of the sections will automatically stop the grading.
Good luck to you and don’t forget your author file !