17.2.126. MPI_File_read

MPI_File_read - Reads a file starting at the location specified by the individual file pointer (blocking, noncollective).

17.2.126.1. SYNTAX

17.2.126.1.1. C Syntax

#include <mpi.h>

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

17.2.126.1.2. 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

17.2.126.1.3. 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

17.2.126.2. INPUT PARAMETERS

  • fh: File handle (handle).

  • count: Number of elements in buffer (integer).

  • datatype: Data type of each buffer element (handle).

17.2.126.3. OUTPUT PARAMETERS

  • buf: Initial address of buffer (integer).

  • status: Status object (status).

  • IERROR: Fortran only: Error status (integer).

17.2.126.4. DESCRIPTION

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. 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.

17.2.126.5. ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler is called. For MPI I/O function errors, the default error handler is set to MPI_ERRORS_RETURN. The error handler may be changed with MPI_File_set_errhandler; the predefined error handler MPI_ERRORS_ARE_FATAL may be used to make I/O errors fatal. Note that MPI does not guarantee that an MPI program can continue past an error.