OpenMPI: error: ‘MPI’ has not been declared

Question

Always get the following errors while running the OpenMPI command "mpicxx hello_cxx.cc -o hello"

hello_cxx.cc: In function ‘int main(int, char**)’: 
hello_cxx.cc:25:5: error: ‘MPI’ has not been declared
     MPI::Init();
     ^~~ hello_cxx.cc:26:12: error: ‘MPI’ has not been declared
     rank = MPI::COMM_WORLD.Get_rank();
            ^~~ hello_cxx.cc:27:12: error: ‘MPI’ has not been declared
     size = MPI::COMM_WORLD.Get_size();
            ^~~ hello_cxx.cc:31:5: error: ‘MPI’ has not been declared
     MPI::Finalize();
     ^~~

To help it would really help to see the code of and not only the couple lines that you put up here. — Kaveh Vahedipour
– Kaveh Vahedipour, Commented Sep 25, 2017 at 19:49
Also it would help to know what OS, which version of OpenMPI you use. — Kaveh Vahedipour
– Kaveh Vahedipour, Commented Sep 25, 2017 at 20:00
I have tried 3 different versions, all are version 2 or later in Ubuntu Kylin 17.04. — Muhammad Rabiul Alam
– Muhammad Rabiul Alam, Commented Oct 3, 2017 at 5:34
Since it didn't help at all, I tried installing a fresh "Ubuntu GNOM 17.04" OS and "openmpi-2.1.1". But, it didn't help following a regular process of installation and then enabling "--enable-mpi-cxx". So, after installation and enabling "--enable-mpi-cxx" I rebuild it with "sudo make install" command and it worked fine. — Muhammad Rabiul Alam
– Muhammad Rabiul Alam, Commented Oct 3, 2017 at 5:43

Gilles Gouaillardet · Accepted Answer · 2017-09-26 00:29:45Z

4

Your application is using MPI C++ bindings. Keep in mind C++ bindings have been removed from the MPI standard.

From an Open MPI point of view, C++ bindings are still here, but they are no more built be default since Open MPI 2.0.0.

So if you are using Open MPI 2.0.0 or later, you first need to make sure C++ bindings were built. If not, you need to rebuild Open MPI, and configure with the --enable-mpi-cxx option.

On the long term, you should really move away from MPI C++ bindings. You can either use plain C bindings, or explore alternate C++ bindings such as the popular Boost:MPI library.

answered Sep 26, 2017 at 0:29

Gilles Gouaillardet

8,47111 gold badges26 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Zihao wang · Accepted Answer · 2017-12-22 05:07:31Z

0

I also meet the problem,but I don't have root privileges. As the before answer mentioned , Open MPI 2.0.0 has changed the build mode.So you just need to change the grammar.

I meet the error:

error: ‘MPI’ has not been declared

mpifile = MPI::FILE_NULL;

From the openmp 2.0 api:

http://mpi-forum.org/docs/mpi-2.0/mpi-20-html/node217.htm#Node217

I find the new error handle is MPI_FILE_NULL.I change it directly in my code and then it works.

The next link is about the Deprecated since MPI-2.2:

http://mpi-forum.org/docs/mpi-2.2/mpi22-report/node328.htm#Node328

answered Dec 22, 2017 at 5:07

Zihao wang

12 bronze badges

Collectives™ on Stack Overflow

OpenMPI: error: ‘MPI’ has not been declared

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related