# mpiexec -n 2 python ex-2.01.py

# Process 0 sends a message to process 1

# --------------------------------------------------------------------

import array

from mpi4py import MPI

if MPI.COMM_WORLD.Get_size() < 2:
    raise SystemExit from None

# --------------------------------------------------------------------

s = b"Hello there"

msg = array.array("B", b"\0" * 20)
tag = 99
status = MPI.Status()

myrank = MPI.COMM_WORLD.Get_rank()

if myrank == 0:
    msg[: len(s)] = array.array("B", s)
    MPI.COMM_WORLD.Send([msg, len(s) + 1, MPI.CHAR], 1, tag)
elif myrank == 1:
    MPI.COMM_WORLD.Recv([msg, 20, MPI.CHAR], 0, tag, status)

# --------------------------------------------------------------------

if myrank == 1:
    assert list(msg[: len(s)]) == list(s)
    assert msg[len(s)] == 0
    assert status.source == 0
    assert status.tag == tag
    assert status.error == MPI.SUCCESS
    assert status.Get_count(MPI.CHAR) == len(s) + 1

# --------------------------------------------------------------------