FILE 0-malloc_checked.c is a function that allocates memory using malloc.
FILE 1-string_nconcat.c is a function that concatenates two strings.
FILE 2-calloc.c is a function that allovates memory for an array, using malloc.
FILE 3-array_range.c is a function that creates an array of integers.
FILE 100-realloc.c is a function that reallocates a memory block using malloc and free.
FILE 101-mul.c is a program that multiplies two positive numbers.