0

Recently, i started learning about MPI programming and I have tried to program it on both Linux and Windows OS. I do not have any problem running the MPI application on Linux, however, i stumbled upon expression must have a constant value error on Visual Studio

For example, i'm trying to get the world_size via the MPI_Comm_size(MPI_COMM_WORLD, &world_size); and create an array based on the world_size (for example)

Code Sample :

#include <mpi.h>
      int world_size;
      MPI_Comm_size(MPI_COMM_WORLD, &world_size);

      int database[world_size]; //error occured here

However, when i'm running it on Linux, it is working perfectly fine as i'm able to execute the code while stating the number of processes i wish to have. Am i missing out anything? I followed this particular youtube link that taught me how to install MS-MPI on my Visual Studio 2015.

Any help would be greatly appreciated.

astral zhang
  • 3
  • 4

1 Answers1

0

Automatic array sizing using non const values actually works with gcc (https://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html). However, it's considered a bad idea because (as you've just experienced) your code won't be portable anymore. You just need to change your code to create an array using new. You might want to generate an error to make sure your code is portable: Disable variable-length automatic arrays in gcc

aquinas
  • 23,318
  • 5
  • 58
  • 81