Object-oriented programming and shared memory

I am developing a object-oriented application and use programming C++ in

I need to develop an class where its methods are different processes,
that they need have to access the same attribute (variable) of the class. I
decided to use the feature of shared memory, however I have not had success.
I find that the reason is the mode as the attributes of the class are
called. I declared the attribute as " volatile float attribute".

I made some attempts without success. One that me seemed interesting to
illustrate the problem was the following one:

I did not use object-oriented programming C++. I created a program in
standard language C and the previous methods had been transformed into
functions. I used memory shared and in the end the great surprise: when I
compiled the program with compiler C, the program functioned. Already when I
compiled with the compiler C++, I got same the previous errors when it was
using object-oriented class.

Please, somebody already had some similar experience? Somebody can help
me? I do not know more what to makeā€¦