例子很容易懂,关键是在每个fprintf后面都需要加一个fflush(stderr),否则不能在mpi模式下运行。
#include"mpi.h"
#include
int main(int argc, char** argv)
{
int rank, value, size;
value = 1;
MPI_Status status;
char name[MPI_MAX_PROCESSOR_NAME];
int len;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
//printf("let's begin.....\n");
MPI_Get_processor_name(name,&len);
do
{
if (rank == 0)
{
fprintf(stderr, "\nPlease give me a number=");
fflush(stderr);
scanf_s("%d", &value);
fprintf(stderr, "%d read <-<- (%d)\n", rank, value);
fflush(stderr);
if (size > 1)
{
MPI_Send(&value, 1, MPI_INT, rank + 1, 0, MPI_COMM_WORLD);
fprintf(stderr, "%d send (%d)->-> %d\n", rank, value, rank + 1);
fflush(stderr);
}
}
else
{
MPI_Recv(&value, 1, MPI_INT, rank - 1, 0, MPI_COMM_WORLD, &status);
fprintf(stderr, "%d receive(%d)<-<- %d\n", rank, value, rank - 1);
fflush(stderr);
if (rank < size - 1)
{
MPI_Send(&value, 1, MPI_INT, rank + 1, 0, MPI_COMM_WORLD);
fprintf(stderr, "%d send (%d)->-> %d\n", rank, value, rank + 1);
fflush(stderr);
}
}
MPI_Barrier(MPI_COMM_WORLD);
}while (value >= 0);
/*if (rank == 0)
{
//fprintf(stderr, "name:%s length:%d\n", name, len);
fprintf(stderr, "\n please give me a number:");
fflush(stderr);
scanf_s("%d", &value,1);
}*/
MPI_Finalize();
return 0;
printf("bye-bye!");
}