Update C++ function and simulink

Hi, I have 2 questions. When i only change the C-code it will not be updated in the simulation?

Example:

int GetADC()

{

   return 10;

}

Next time I change 10 to 5 and when I rerun the model it still return 10. It only update when I change some thing in the stateflow/Simulink model.

Is it possible to access the Matlab workspace or Simulink variable from inside the c function?

Whit kind regards,

Ralf