DESCRIPTION
       The malloc() function allocates size bytes and 
       returns a pointer to the allocated memory.  The 
       memory is not initialized.  If size is  0,  then 
       malloc()  returns either NULL, or a unique pointer 
       value that can later be successfully passed to 
       free().

       The free() function frees the memory space pointed  
       to  by  ptr,  which must  have  been  returned by a 
       previous call to malloc(), calloc(), or realloc().  
       Otherwise, or if free(ptr) has already been called  
       before, undefined behavior occurs.  If ptr is NULL, 
       no operation is performed.