Question

I have this definition for my structure:

struct localframevelo
{
    double ivelo; //i(x) component of velocity
    double cvelo; //c(y) component of velocity
    double rvelo; //r(z) component of velocity
    double speed; //total magnitude of velocity

    localframevelo()
    {
        ivelo = 0;
        cvelo = 0;
        rvelo = 0;
        speed = 0;
    }
    localframevelo(double init_ivelo, double init_cvelo, double init_rvelo)
    {
        ivelo = init_ivelo;
        cvelo = init_cvelo;
        rvelo = init_rvelo;
        speed = sqrt(pow(ivelo, 2.0) + pow(cvelo, 2.0) + pow(rvelo, 2.0));
    }
};

Here is a class that I am trying to use the default constructor of localframevelo in:

    class missionprofile
    {
    //misison waypoints structure************************
    private:
        double stdholdtime; // 0.25 second within tolerance radius to "reach" a waypoint
        double stdtolrad; // 0.5 meter tolerance radius (error magnitude) to "be at" a waypoint
        localframevelo stdvelo;
        waypoint missionwaypoints[MAXLISTLENGTH];
        int numwaypoints;

    public:
        missionprofile();
        missionprofile(int points, double StdHoldTime, double StdTolRadius, localframevelo StdVelo);

};

Here is the implementation of the default constructor for the class that I am trying to call the localframevelo’s default constructor:

missionprofile::missionprofile()
{
    numwaypoints = 0;
    stdholdtime = 0;
    stdtolrad = 0;
    stdvelo();          //ERROR
}

I get this error: call of an object of a class type without appropriate operator() or conversion functions to pointer-to-function type. I am using the mbed compiler, what is wrong with my code?

Answer 1

You can safely remove this line:

stdvelo();   

In the context of a function body, this is interpreted as a call to the operator()() of an instance of localframevelo, not an initialization. The data member will be default constructed anyway without any explicit initialization. But what you should really be doing is to initialize your data members in the constructor’s initialization list:

missionprofile::missionprofile() 
  : numwaypoints(),
    stdholdtime(),
    stdtolrad(),
    stdvelo()
{
}

And similarly for localframevelo‘s constructors and the other missionprofile constructor.