Separate HTML for Basic Foil 24 Hello World:C Example of Send and Receive

Basic HTML version of Foils prepared 10 Oct 1995

Foil 24 Hello World:C Example of Send and Receive

From Fox Presentation Fall 1995 CPS615 Basic Simulation Track for Computational Science -- Fall Semester 95. by Geoffrey C. Fox

#include "mpi.h"

main( int argc, char **argv )

{

char message[20];
int i, rank, size, tag=137; # Any value of type allowed
MPI_Status status;
MPI_Init (&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size); # Number of Processors
MPI_Comm_rank(MPI_COMM_WORLD, &rank); # Who is this processor
if( rank == 0 ) { # We are on "root" -- Processor 0
- strcpy(message,"Hello MPI World"); # Generate message
- for(i=1; i<size; i++) # Send message to size-1 other processors
- MPI_Send(message, strlen(message)+1, MPI_CHAR, i, tag, MPI_COMM_WORLD);
}
else
- MPI_Recv(message,20, MPI_CHAR, 0, tag, MPI_COMM_WORLD, &status);
printf("This is a message from node %d saying %s\n", rank, message);
MPI_Finalize();

}