Problem in sending vector <string> by MPI c++

[vineet pratap]

Hello can somebody help me to sending it................

#include <iostream>
#include <vector>
#include <string>
#include"mpi.h"
using namespace std;

main(int argc, char *argv[])
{

        MPI::Status status;
        MPI::Init(argc,argv);
        int myrank = MPI::COMM_WORLD.Get_rank();
        int numprocs = MPI::COMM_WORLD.Get_size();
        MPI_Datatype strtype;
        //int blocklen=16;
        //MPI_Aint disp[3]={0,16,32};
        MPI_Type_contiguous(16,MPI::CHAR,&strtype);
        MPI_Type_commit(&strtype);
   vector<string> SS;
 if(myrank == 0){
   SS.push_back("The number is 10");
   SS.push_back("The number is 20");
   SS.push_back("The number is 30");

   cout << "At root Node: " << endl;

   int ii;
   for(ii=0; ii < SS.size(); ii++)
   {
      cout << SS[ii] << endl;
   }
        //MPI_Type_contiguous(16,MPI::CHAR,strtype);
        MPI::COMM_WORLD.Send(&SS[0],3,strtype, 1, 1);
 }
else{
        SS.reserve(3);
        MPI::COMM_WORLD.Recv(&SS[0],3,strtype,0,1);
   int ii;
         cout << "At worker Node: " << endl;
   for(ii=0; ii < SS.size(); ii++)
   {
      cout << SS[ii] << endl;
   }
 }
        MPI::Finalize();
}

Now My O/P is:

$ mpicxx vecDemo.cpp -o vDemo.out -DMPICH_IGNORE_CXX_SEEK
$ mpirun -np 2 ./vDemo.out
At root Node:
The number is 10
The number is 20
The number is 30
At worker Node:
$

BUT i want O/P like.......

$ mpirun -np 2 ./vDemo.out
At root Node:
The number is 10
The number is 20
The number is 30
At worker Node:
The number is 10
The number is 20
The number is 30
$

[Daved]

I don't know anything about MPI, but strings can be stored in dynamic memory, especially ones that are more than 15 characters long. It seems like you're trying to send the string as raw data.

Perhaps a vector<vector<char> > would be more appropriate?

[ryanrigdon]

I'm similar to Daved in knowing nothing about MPI, but I have another possible suggestion. When you access an element of the vector you can call the c_str() function get raw text.

Like this:

MPI::COMM_WORLD.Send(SS[0].c_str(), 3, strtype, 1, 1);

That will make the first parameter of MPI::COMM_WORLD.Send() a char* rather than the address of a string.