C++ Project on STM32CubeIDE

[DUrbano]

Hi,

my name is Davide Urbano and I'm using STM32CubeIDE making only C projects; now I'd like to create a C++ project so going to File->New ->STM32 Project and selecting my stm32 mcu, I check for a C++ language project. The project created has only C files so when I include cpp files with my own class, I have to change the main extension file from .c to .cpp to compile with g++; the problem is that my class is not correctly recognized ( function declared public in my class, are not seen in the same class from the compiler) and I'd like to know what's wrong...there's another missing setting? Could you suggest me how can I correctly use my cpp files?

Regards

Davide Urbano

[Pavel A.]

This is very simple in the latest CubeIDE. Just create a new project: New-> STM32 project; then select "C++" here:

Note that you don't want to touch the Cube-generated main.c and other c files at all.

Just add all your C++ code in your own file with cpp suffix and call it from main.c. Of course, don't forget extern "C".

--pa

[DUrbano]

Ok...all it's clear...but if I don't rename main file from .c to .cpp the class imported is not seen and I get the error " error: unknown type name 'class' "...Do I miss something?

[Pavel A.]

Yes, sure. Because plain C files are compiled with C compiler which does not know what is class.

You use classes in your .cpp files, these will be compiled with g++.

-- pa

[DUrbano]

Perfect...is there a possibility to use my class in main.c file without rename it? Thanks for your support and your patience...

[Cartu38 OpenDev]

May help There is a plan to allow STM32cubeMX for generating main.cpp instead of .c only ?

[Pavel A.]

Davide, the C compiler simply does not know what is class.

But it can call external functions with C interface (that you define in your C++ files as extern "C" ) and your C++ code can call functions exported from main.c, and use external variables exported by main.c.

The simplest is:

// main.c
 
int main(void)
{
   ..............
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
 
  extern void cpp_main();
  cpp_main();
  while (1)
  {
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}
 
//------------------------------
 
// cppmain.cpp
 
#include <cstdio>
 
extern "C" void cpp_main()
{
   // Think that *THIS* is your main()
   printf("hi from c++");
}

[Pavel A.]

> May help There is a plan to allow STM32cubeMX for generating main.cpp instead of .c only ?

With separate main.c and C++ files (which I support), it is extremely important to NOT name the latter "main.cpp". Choose a different name.

Hope this is obvious, but for a beginner nothing is too obvious or too easy.

As for "main.hpp" it could be like following:

#pragma once
 
#ifndef __cplusplus
#error Do not include this in C files
#endif
 
extern "C" {
#include "main.h"
}
 
// your c++ stuff.........
 

-- pa

[DUrbano]

Thanks to all for having solved my problem...and thanks for the patience