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.TH MPI_Attr_get 3 "1/6/1997" " " "MPI"
.SH NAME
MPI_Attr_get \- Retrieves attribute value by key
.SH SYNOPSIS
.nf
#include "mpi.h"
int MPI_Attr_get ( comm, keyval, attr_value, flag )
MPI_Comm comm;
int keyval;
void *attr_value;
int *flag;
.fi
.SH INPUT PARAMETERS
.PD 0
.TP
.B comm
- communicator to which attribute is attached (handle)
.PD 1
.PD 0
.TP
.B keyval
- key value (integer)
.PD 1
.SH OUTPUT PARAMETERS
.PD 0
.TP
.B attr_value
- attribute value, unless
.I flag
= false
.PD 1
.PD 0
.TP
.B flag
- true if an attribute value was extracted; false if no attribute is
associated with the key
.PD 1
.SH NOTES
Attributes must be extracted from the same language as they were inserted
in with
.I MPI_ATTR_PUT
. The notes for C and Fortran below explain why.
.SH NOTES FOR C
Even though the
.I attr_value
arguement is declared as
.I void *
, it is
really the address of a void pointer. See the rationale in the
standard for more details.
.SH NOTES FOR FORTRAN
All MPI routines in Fortran (except for
.I MPI_WTIME
and
.I MPI_WTICK
) have
an additional argument
.I ierr
at the end of the argument list.
.I ierr
is an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with the
.I call
statement.
All MPI objects (e.g.,
.I MPI_Datatype
,
.I MPI_Comm
) are of type
.I INTEGER
in Fortran.
The
.I attr_value
in Fortran is a pointer to a Fortran integer, not
a pointer to a
.I void *
.
.SH ERRORS
All MPI routines (except
.I MPI_Wtime
and
.I MPI_Wtick
) return an error value;
C routines as the value of the function and Fortran routines in the last
argument. Before the value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job. The error handler
may be changed with
.I MPI_Errhandler_set
; the predefined error handler
.I MPI_ERRORS_RETURN
may be used to cause error values to be returned.
Note that MPI does
.B not
guarentee that an MPI program can continue past
an error.
.PD 0
.TP
.B MPI_SUCCESS
- No error; MPI routine completed successfully.
.PD 1
.PD 0
.TP
.B MPI_ERR_COMM
- Invalid communicator. A common error is to use a null
communicator in a call (not even allowed in
.I MPI_Comm_rank
).
.PD 1
.PD 0
.TP
.B MPI_ERR_OTHER
- Other error; the error code associated with this error
indicates an attempt to use an invalue keyval.
.PD 1
.SH LOCATION
attr_getval.c
|
