#include <mpi.h>
#include <stdio.h>
#define SIZE 4

int main(int argc, char *argv[]) 
{
   int nprocs, myrank, source=0, dest, tag=1, i, j;
   int blockcounts[2];
      
   /* PartStruct is a derived data type with two kinds of variables
      (int and double)                                               */
   typedef struct 
      {
         int class, subclass;
         double dim;
      } PartStruct;
          
   PartStruct recvbuf[SIZE], sendbuf[SIZE];

   MPI_Datatype particletype, orgdatatype[2];
          
   /* MPI_Aint type used to be consistent with syntax of MPI_Type_extent
      routine                                                            */
          
   MPI_Aint offsets[2], extent;
   MPI_Status stat;
          
   MPI_Init(&argc,&argv);
   MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
   MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
          
   /* Allocates the 2 MPI_INT for the fields class  and subclass */
          
   offsets[0] = 0;
   orgdatatype[0] = MPI_INT;
   blockcounts[0] = 2;
          
   /* Allocates space for 1 MPI_DOUBLE field dim after figuring out
   the offset by getting size of MPI_INT                           */
          
   MPI_Type_extent(MPI_INT, &extent);
   offsets[1] = 2 * extent;
   orgdatatype[1] = MPI_DOUBLE;
   blockcounts[1] = 1;
          
   /* Now define structured type and commit it */
          
   MPI_Type_struct(2, blockcounts,offsets,  orgdatatype, &particletype);
   MPI_Type_commit(&particletype);
          
   /* Initialize the sendbuf structure and then send it to each task */

   if(myrank == 0) 
     {
       for(i = 0; i < SIZE; i++) 
         {
           sendbuf[i].class = i+100;
           sendbuf[i].subclass = i+200;
           sendbuf[i].dim = 1.0 *(i+1);
         }
     
       for(i=0; i<nprocs; i++)
         MPI_Send(sendbuf, SIZE, particletype, i, tag, MPI_COMM_WORLD);
     }
  
   MPI_Recv(recvbuf, SIZE, particletype, source, tag, MPI_COMM_WORLD, &stat);
          
   /* Print a sample of what was received */

  for(i = 0; i < SIZE; i++)
    printf("rank= %d %d %d %f \n", myrank, recvbuf[i].class,
           recvbuf[i].subclass, recvbuf[i].dim);
  
  MPI_Finalize();
}