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  1. #include <stdio.h>
  2. #include <mpi.h>
  3. int main(int argc, char *argv[])
  4. {
  5.     const int tag = 42; /* Message tag */
  6.     int id, ntasks, source_id, dest_id, err, i;
  7.     MPI_Status status;
  8.     int msg[2]; /* Message array */
  9.  
  10.     err = MPI_Init(&argc, &argv); /* Initialize MPI */
  11.     if (err != MPI_SUCCESS)
  12.     {
  13.         printf("MPI initialization failed!\n");
  14.         exit(1);
  15.     }
  16.     err = MPI_Comm_size(MPI_COMM_WORLD, &ntasks); /* Get nr of tasks */
  17.     err = MPI_Comm_rank(MPI_COMM_WORLD, &id);     /* Get id of this process */
  18.     if (ntasks < 2)
  19.     {
  20.         printf("You have to use at least 2 processors to run this program\n");
  21.         MPI_Finalize(); /* Quit if there is only one processor */
  22.         exit(0);
  23.     }
  24.     if (id == 0)
  25.     { /* Process 0 (the receiver) does this */
  26.         for (i = 1; i < ntasks; i++)
  27.         {
  28.             err = MPI_Recv(msg, 2, MPI_INT, MPI_ANY_SOURCE, tag, MPI_COMM_WORLD,
  29.                            &status);       /* Receive a message */
  30.             source_id = status.MPI_SOURCE; /* Get id of sender */
  31.             printf("Received message %d %d from process %d\n", msg[0], msg[1],
  32.                    source_id);
  33.         }
  34.     }
  35.     else
  36.     {                    /* Processes 1 to N-1 (the senders) do this */
  37.         msg[0] = id;     /* Put own identifier in the message */
  38.         msg[1] = ntasks; /* and total number of processes */
  39.         dest_id = 0;     /* Destination address */
  40.         err = MPI_Send(msg, 2, MPI_INT, dest_id, tag, MPI_COMM_WORLD);
  41.     }
  42.  
  43.     err = MPI_Finalize(); /* Terminate MPI */
  44.     if (id == 0)
  45.         printf("Ready\n");
  46.     exit(0);
  47.     return 0;
  48. }
Success #stdin #stdout #stderr 0.27s 40812KB
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Standard input is empty
stdout
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Standard output is empty
stderr
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Error: unexpected symbol in "int main"
Execution halted
https://ideone.com/ShJRjF
language:
R (R 3.5.2)
created:
13 days ago
visibility:
public

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