MPI test program, sending messages in a ring

mpi_ring.cc

#include <mpi.h>

int main(int argc, char** argv)
{
	// Initialize the MPI environment
	MPI_Init(NULL, NULL);

	// Get the number of processes
	int world_size;
	MPI_Comm_size(MPI_COMM_WORLD, &world_size);

	// Get the rank of the process
	int world_rank;
	MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);

	// Get the name of the processor
	char processor_name[MPI_MAX_PROCESSOR_NAME];
	int name_len;
	MPI_Get_processor_name(processor_name, &name_len);

	// Print off a hello world message
	printf("Hello world from processor %s, rank %d"
		" out of %d processors\n",
		processor_name, world_rank, world_size);

	int token;
	if (world_rank != 0) {
		MPI_Recv(&token, 1, MPI_INT, world_rank - 1, 0,
			MPI_COMM_WORLD, MPI_STATUS_IGNORE);
		printf("Process %d received token %d from process %d\n",
			world_rank, token, world_rank - 1);
	}
	else {
		// Set the token's value if you are process 0
		token = 112;
	}
	MPI_Send(&token, 1, MPI_INT, (world_rank + 1) % world_size,
		0, MPI_COMM_WORLD);
	// Now process 0 can receive from the last process.
	if (world_rank == 0) {
		MPI_Recv(&token, 1, MPI_INT, world_size - 1, 0,
			MPI_COMM_WORLD, MPI_STATUS_IGNORE);
		printf("Process %d received token %d from process %d\n",
			world_rank, token, world_size - 1);
	}

	// Finalize the MPI environment.
	MPI_Finalize();
}

mpic++ mpi.cc
mpiexec -n 8 a.out

thanks to you, I was able to familiarize myself with the ring principle in mpi, thank you!)