MPI only compiles in Visual Studio debug section - c++

Question

I have this program
#include <stdio.h>
#include <mpi.h>
#include <iostream>
using namespace std;
int main(int argc, char* argv[])
{
int size;
int rank;
MPI_Init(NULL, NULL);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
printf("Hello, World!");
cout << MPI_Comm_rank << " " << MPI_Comm_size << endl;
MPI_Finalize();
return 0;
}
When I debug this in Microsoft Visual Studios it works just fine. But when I try it in the command prompt or any terminal I get this error,
Project_1.cpp:2:10: fatal error: mpi.h: No such file or directory
2 | #include <mpi.h>
| ^~~~~~~
compilation terminated.
I have g++ installed already and it works with other programs just fine. I have MPI installed too. Was able to link it to my Microsoft Visual Studio but it only works in its debug section. I am using a windows computer. Not really sure what to do. Any help would be great thanks.

Answer 1

There are some problem with your program:
You don't define MPI_Comm_rank and MPI_Comm_size but you try to print them in cout. In the following piece of code, I've rewritten your code.
#include <stdio.h>
#include <mpi.h>
#include <iostream>
using namespace std;
int main(int argc, char* argv[])
{
int size;
int rank;
MPI_Init(NULL, NULL);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
printf("Hello, World!");
cout << rank << " " << size << endl;
MPI_Finalize();
return 0;
}
You also need to add the location of mpiexec.exe to your system PATH by :
1- Open Window’s System Properties dialog box => click on Environment Variables
2- Click edit for the Path variable => add C: Program Files\Microsoft MPI\Bin \ (Assuming the default install)
To include the appropriate libraries.
1- The MPI code should be compiled as a Console Application
2- Once you have created the project you need to add the appropriate library
Right-click on the project in the Solution Explorer and go to Properties
Click on VC++ Directories and (assuming the MPI SDK is installed in the default directory) add:
C:/ Program Files (x86)/Microsoft SDKs/Include to the Include Directories
C:/Program Files (x86)/Microsoft SDKs/Lib/x64 or C:/Program Files (x86)/Microsoft SDKs/Lib/x86 to the Library Directories
Depends on whether you wish to compile your code as 32bit or 64bit
3- Click on Linker =>Input
Under Additional Dependencies add msmpi.lib