io4.c

The example for Boor USING MPI2

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

/* example of parallel MPI write into a single file */
#define BUFSIZE 100
int main(int argc, char *argv[])
{
    int i, myrank, buf[BUFSIZE];
    char filename[128];
    MPI_File thefile;
    MPI_Offset offset;

    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
    sprintf(filename, "testfile");
    for (i = 0; i < BUFSIZE; i++)
        buf[i] = myrank * BUFSIZE + i;
    MPI_File_open(MPI_COMM_WORLD, filename,
		  (MPI_MODE_WRONLY | MPI_MODE_CREATE),
		  MPI_INFO_NULL, &thefile);
    MPI_File_set_view(thefile, 0, MPI_INT, MPI_INT, "native", MPI_INFO_NULL);
    offset = myrank * BUFSIZE;
    MPI_File_write_at(thefile, offset, buf, BUFSIZE, MPI_INT,
		      MPI_STATUS_IGNORE);
    MPI_File_close(&thefile);
    MPI_Finalize();
    return 0;
}