FILE 0-create_array.c is a function that creates an array of chars, and initiates it with a specific char.
FILE 1-strdup.c is a function that returns a pointer to a newly allocated space in memory, which contains a copy of the string given as a parameter.
FILE 2-str_concat.c is a function that concatenates two strings.
FILE 3-alloc_grid.c is a function that returns a pointer to a 2 dimensional array of integers.
FILE 4-free_grid.c is a function that frees a 2 dimensional grid previously created by your alloc_grid function.
FILE 100-argstostr.c is a function that concatenates all the arguments of your program.
FILE 101-strtow.c is a function that splits a string into words.