/* example of sequential Unix write into a common file */ 
#include "mpi.h" 
#include <stdio.h> 
#define BUFSIZE 100 
 
int main(int argc, char *argv[]) 
{ 
    int i, myrank, numprocs, buf[BUFSIZE]; 
    MPI_Status status; 
    FILE *myfile; 
 
    MPI_Init(&argc, &argv); 
    MPI_Comm_rank(MPI_COMM_WORLD, &myrank); 
    MPI_Comm_size(MPI_COMM_WORLD, &numprocs); 
    for (i=0; i<BUFSIZE; i++)	 
	buf[i] = myrank * BUFSIZE + i; 
    if (myrank != 0) 
	MPI_Send(buf, BUFSIZE, MPI_INT, 0, 99, MPI_COMM_WORLD); 
    else { 
	myfile = fopen("testfile", "w"); 
	fwrite(buf, sizeof(int), BUFSIZE, myfile); 
	for (i=1; i<numprocs; i++) { 
	    MPI_Recv(buf, BUFSIZE, MPI_INT, i, 99, MPI_COMM_WORLD, 
		     &status); 
	    fwrite(buf, sizeof(int), BUFSIZE, myfile); 
	} 
	fclose(myfile); 
    } 
    printf("myank: %i before finalize \n",myrank);
    MPI_Finalize(); 
    return 0; 
}