Description

   The type size_t is defined in the header file <stdio.h> as
   follows:

   typedef unsigned int size_t

   The writing begins at the current location in the file. The items
   are written from storage beginning at the location given by the
   first argument. You must also specify the size of an item, in
   bytes.

   If the file pointed to by file_ptr is a record file, the fwrite
   function outputs at least number_items records, each of length
   size_of_item.