0x0B-malloc_free

0x0B. C - malloc, free

Resource

• Dynamic Memory Allocation in C using malloc(), calloc(), free() and realloc().
• Dynamic memory allocation in C - malloc calloc realloc free.
• Dynamic Memory Allocation.
  • Quick overview of malloc & free

Tasks

0. Float like a butterfly, sting like a bee
   • Prototype: char *create_array(unsigned int size, char c);
   • Returns NULL if size = 0.
   • Returns a pointer to the array, or NULL if it fails.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 0-main.c 0-create_array.c -o a
1. The woman who has no imagination has no wings
   • Prototype: char *_strdup(char *str);
   • The _strdup() function returns a pointer to a new string which is a duplicate of the string str.
     • Memory for the new string is obtained with malloc, and can be freed with free.
   • Returns NULL if str = NULL.
   • On success, the _strdup function returns a pointer to the duplicated string. It returns NULL if insufficient memory was available.
   • FYI: The standard library provides a similar function: strdup. Run man strdup to learn more.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 1-main.c 1-strdup.c -o s
2. He who is not courageous enough to take risks will accomplish nothing in life : A function that concatenates two strings.
   • Prototype: char *str_concat(char *s1, char *s2);
   • The returned pointer should point to a newly allocated space in memory which contains the contents of s1, followed by the contents of s2, and null terminated.
   • If NULL is passed, treat it as an empty string.
   • The function should return NULL on faliure.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 2-main.c 2-str_concat.c -o c
3. If you even dream of beating me you'd better wake up and apologize : A function that returns a pointer to a 2 dimensional array of integers.
   • Prototype: int **alloc_grid(int width, int height);
   • Each element of the grid should be initialized to 0.
   • The function should return NULL on faliure.
   • If width or height is 0 or negative, return NULL.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 3-main.c 3-alloc_grid.c -o g
4. It's not bragging if you can back it up : A function that frees a 2 dimensional grid previously created by the alloc_grid function.
   • Prototype: void free_grid(int **grid, int height);
   • Note that we will first compile the alloc_grid file to make sure it compiles.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 4-main.c 3-alloc_grid.c 4-free_grid.c -o f
5. It isn't the mountains ahead to climb that wear you out; it's the pebble in your shoe : A function that concatenates all the arguments of your program.
   • Prototype: char *argstostr(int ac, char **av);
   • Returns NULL if ac == 0 or av == NULL
   • Returns a pointer to a new string, or NULL if it fails.
   • Each argument should be followed by a \n in the new string.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 100-main.c 100-argstostr.c -o args
6. I will show you how great I am : A function that splits a string into words.
   • Prototype: char **strtow(char *str);
   • The function returns a pointer to an array of strings (words).
   • Each element of this array should contain a single word, null-terminated.
   • The last element of the returned array should be NULL.
   • Words are separated by spaces.
   • Returns NULL if str == NULL or str == "".
   • If your function fails, it should return NULL.
   • Compile the code this way: gcc -Wall -pedantic -Werror -Wextra -std=gnu89 101-main.c 101-strtow.c -o strtow