PROGRAM mpi2io

     USE MPI
     IMPLICIT none

     INTEGER :: myrank, nproc,ierr;
     INTEGER, PARAMETER :: dim_buf = 10
     INTEGER :: buf(dim_buf)
     INTEGER :: i, intsize;
     INTEGER(KIND=MPI_OFFSET_KIND) :: offset, file_size
     INTEGER :: fh
     INTEGER :: status(MPI_STATUS_SIZE)
     INTEGER :: filetype

     CALL MPI_Init(ierr);
     CALL MPI_Comm_size(MPI_COMM_WORLD,nproc,ierr)
     CALL MPI_Comm_rank(MPI_COMM_WORLD,myrank,ierr)

     DO i=1,dim_buf
        buf(i) = myrank*dim_buf+i-1;
     END DO

     ! Open the file and write by using individual file pointers:
     ! - use MPI_File_open to access the file "output.dat"; which access mode?
	 ! - use MPI_File_write for storing data, but first call function MPI_File_seek
	 ! -    to define 'offset'; on what values is it depending on?
	 ! - Hint: the function MPI_Type_size may be used to get the data type size
	 ! - do not forget of calling MPI_File_close at the end 
		---

     ! Re-open the file and read by using explicit offset:
     ! - use MPI_File_open to access "output.dat" for reading; which access mode?
		---

	 !- use the function MPI_File_get_size to obtain 'file_size' */
		---
     offset = file_size/nproc*myrank
     write(6,*) "myid ",myrank,"filesize ", file_size, "offset ", offset

	! - use the function MPI_File_read_at for reading
	! - do not forget to close the file at the end */
		---

     ! Write the new file using the mpi_type_create_vector. Use the fileview:
     ! - now every process has a copy of 'buf'
     ! - use MPI_File_open to access "output_mod.dat" with the proper access mode 
     ! - and use the right function for defining the new data type with handle 'filetype'
		---

	! - the function MPI_File_write_all could be used to store data appropriately,
	! - but the function MPI_File_set_view must first be called to use 'filetype'
	! - How will 'offset' be defined ?
	! - the function MPI_File_get_size may be useed to obtain file_size 
		---
     write(6,*) "myid ", myrank, "filesize of the second file written", file_size, "offset", offset

     CALL MPI_Type_free(filetype,ierr)
     CALL MPI_File_close(fh,ierr) 
     CALL MPI_Finalize(ierr)

END PROGRAM mpi2io