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C | FORTRAN-legacy | FORTRAN-2008

MPI_Comm_group

Definition

MPI_Comm_group gets the group of processes of the given communicator.

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int MPI_Comm_group(MPI_Comm communicator,
                   MPI_Group* group);

Parameters

communicator
The MPI communicator to explore.
group
A pointer on the variable in which store the group of processes of the communicator given.

Returned value

The error code returned from the communicator group retrieval.

MPI_SUCCESS
The routine successfully completed.

Example

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#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>

/**
 * @brief Illustrates how to obtain the group of processes of a communicator.
 **/
int main(int argc, char* argv[])
{
    MPI_Init(&argc, &argv);

    // Get the group from the default communicator
    MPI_Group group;
    MPI_Comm_group(MPI_COMM_WORLD, &group);

    // Get the size of the group
    int size;
    MPI_Group_size(group, &size);

    // Each process prints the number of processes in that group
    printf("We are %d MPI processes in the group of the default communicator MPI_COMM_WORLD.\n", size);

    MPI_Finalize();

    return EXIT_SUCCESS;
}