/* test of Broadcast communication in MPI */ 

#include "mpi.h" 
#include <iostream.h> 
#include <string.h> 

int main(int argc, char **argv) 
{ 
   char buff[128]; 
   int secret_num;

   int numprocs; 
   int myid; 
   int i; 

   MPI_Status stat; 

   MPI_Init(&argc,&argv); 
   MPI_Comm_size(MPI_COMM_WORLD,&numprocs); 
   MPI_Comm_rank(MPI_COMM_WORLD,&myid); 

   if ( argc == 1 )
   {
      if ( myid == 0 )
         cout << "Usage: mpirun -np 4 ./BCast SECRET-CODE" << endl;

      MPI_Finalize();
      exit(1);
   }

   if ( myid == 0 ) 
   { 
      cout << "WE have " << numprocs << " processors" << endl;

      secret_num = atoi(argv[1]);
   }

   // ------------------------------------------
   // Node 0 shares the secret with everybody
   // ------------------------------------------

   MPI_Bcast (&secret_num, 1, MPI_INT, 0, MPI_COMM_WORLD);
 
   if ( myid == 0 )
   {
      for( i = 1; i < numprocs; i++) 
      { 
         MPI_Recv(buff, 128, MPI_CHAR, i, 0, MPI_COMM_WORLD, &stat); 
         cout << buff << endl;
      } 
   } 
   else 
   { 
      sprintf(buff, "Processor %d knows the secret code: %d",
			myid, secret_num);
      MPI_Send(buff, 128, MPI_CHAR, 0, 0, MPI_COMM_WORLD); 
   } 

   MPI_Finalize(); 
}