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MPI_File_read.3.rst

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MPI_File_read

:ref:`MPI_File_read` |mdash| Reads a file starting at the location specified by the individual file pointer (blocking, noncollective).

SYNTAX

C Syntax

#include <mpi.h>

int MPI_File_read(MPI_File fh, void *buf,
     int count, MPI_Datatype datatype, MPI_Status *status)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_READ(FH, BUF, COUNT,
     DATATYPE, STATUS, IERROR)
     <type>  BUF(*)
     INTEGER FH, COUNT, DATATYPE, STATUS(MPI_STATUS_SIZE),IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_File_read(fh, buf, count, datatype, status, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     TYPE(*), DIMENSION(..) :: buf
     INTEGER, INTENT(IN) :: count
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     TYPE(MPI_Status) :: status
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

  • fh: File handle (handle).
  • count: Number of elements in buffer (integer).
  • datatype: Data type of each buffer element (handle).

OUTPUT PARAMETERS

  • buf: Initial address of buffer (integer).
  • status: Status object (status).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_File_read` attempts to read from the file associated with fh (at the current individual file pointer position maintained by the system) a total number of count data items having datatype type into the user's buffer buf. The data is taken out of those parts of the file specified by the current view. :ref:`MPI_File_read` stores the number of data-type elements actually read in status. All other fields of status are undefined.

It is erroneous to call this function if MPI_MODE_SEQUENTIAL mode was specified when the file was opened.

ERRORS