The best strategy to convert this C code(structs) into C++(classes+objects) ?

Question

Hi,

I have a old C code which contains a bunch of structs which I want to turn it into proper C++ code i.e object-oriented.

C/C++ code snippet:

struct Sensors {
    uint16_t type;
    float    value;
    bool     valid;
};
struct RoomControllers {
    Sensors sensor[MAX_NUM_SENSORS];
    float   targetTemperature;
    bool    currentlyHeating;
    float   targetHumidity;
    bool    currentlyHumidifying;
};

int main() {

    RoomControllers roomController = { {0},19.0,false,50.0,false };

This is my progress so far:

class Sensors {
public:
    Sensors(uint16_t typ, float val, bool vali) :type{typ}, value{val}, valid{vali}{};
    Sensors(uint16_t typ, float val) :type{typ}, value{val}{};
    Sensors(uint16_t typ) :type{typ} {};// all constructors defined
    Sensors() = default; // defaulted default constructor
    
    friend class RoomControllers; // RoomControllers can access all data from Sensors

protected:
    uint16_t type=0;
    float    value=0;
    bool     valid{};
    uint16_t MAX_NUM_SENSORS{ 5 };
    enum { INVALID, TEMPERATURE, HUMIDTY };
    enum { NO_CHANGE, HEATING_STATUS_CHANGED, HUMIDIFIER_STATUS_CHANGED };
    enum { NEW_SENSOR, SENSOR_NOT_VALID, MAX_SENSORS_REACHED };
    enum { OK, INVALID_SENSOR_SELECTED };
};

class RoomControllers :public Sensors
{
public:
    RoomControllers(Sensors sensor1);
    void printStates() const;
    void setTemperatureTarget();
    void setHumidityTarget();
    uint8_t checkValues();
    uint8_t newSensor();
    uint8_t updateSensor();

    void checker(); // tidy up bulky switch statements

private:
    float   targetTemperature=19.0; // default initialisation
    bool    currentlyHeating{false};
    float   targetHumidity=50;
    bool    currentlyHumidifying{false};
    std::array<Sensors, 5> sensors; // C-style array replaced by C++ array
    static int32_t counter; // static variable for array indexing
};

int32_t RoomControllers::counter{}; //variable must be initialised to 0 outside class

RoomControllers::RoomControllers(Sensors sensor1)
{
        sensors[counter] = sensor1;
        ++counter;   
}

 My question is how can I place many Sensors objects inside the array in RoomControllers from the int main() function(just like it was using the structs in the C code)? Because the constructor as it is for the RoomControllers only takes one object.

Answer 1

There are plenty of ways to do that.

You can create a new constructor for RoomControllers that accepts an std::vector<Sensors> so you can pass in all the Sensorss (what is the plural of Sensors, lol? --> Probably the correct name for that class should be Sensor -- singular, not plural).

Another option is to create a new function to add a new Sensors to your existing list, e.g.

void AddSensors(Sensors sensors);

In C++ you have dynamic collections (such as the already mentioned std::vector). Are you sure you want to have a static sized collection that has a fixed size all the time?

Comments

thanks man, I'll have a look. The array has to be fixed to 5 as that is the max sensors I am supposed to use.