size_t fwrite (const void * buffer, size_t size, size_t count, FILE * stream);
stream is the file you want to write, the suffix name is specified by yourself, count is the maximum number of bytes written
write (reinterpret_cast <char *> (&one_object), sizeof (one_object));
This is written to the hard disk in binary mode
one_object is the object to be written, haha