Passing a vector to constructor of a class-CodePudding

Note: I have seen all the similar questions on this website, but I still could not make this work.

I made a class for astronomical coordinates and I am trying to overload the << operator to store user input in the class. The two coordinates (right ascension and declination) are vectors of doubles.

When I call the parametrised constructor, I get the following two errors: "call of an object of a class type without appropriate operator() or conversion functions to pointer-to-function type" and "no match for call to '(coordinates) (std::vector&, std::vector&)'". It seems like I have to pass the vectors by reference, but I haven't managed to. How do I make it work?

Here is the code:

#include <iostream>
#include <vector>
#include <string>
#include <sstream>

class coordinates {
protected: 
    std::vector<double> right_ascension, declination; 
public:
    std::vector<double> zero_vector{(1,0)};
    coordinates(): right_ascension{zero_vector}, declination{zero_vector} {} // Default constructor
    coordinates(std::vector<double> ra, std::vector<double> dec) : right_ascension{ra}, declination{dec} {} // Paramterised constructor
    ~coordinates(){std::cout << "Calling coordinates destructor" << std::endl;}

    friend std::istream& operator>>(std::istream &is, coordinates &coords);
};

std::istream& operator>>(std::istream &is, coordinates &coord){    
    // Read imput from string stream "1.1 2.2 3.3; 4.4 5.5 6.6"
    std::string right_ascension;
    double hh, mm, sec;
    std::vector<double> ra, dec;
    
    // Read data
    std::stringstream ss("");
    std::getline(is, right_ascension, ';');
    ss.str("");
    ss << right_ascension; 
    ss >> hh >> mm >> sec;
    ra.push_back(hh);
    ra.push_back(mm);
    ra.push_back(sec);

    is >> hh >> mm >> sec;
    dec.push_back(hh);
    dec.push_back(mm);
    dec.push_back(sec);
    
    coord(ra, dec); // Here I get the two errors I mentioned
    return is;
}

int main() {
    coordinates coords;
    std::cout << "Input numbers (hh mm ss; hh ss mm)";
    std::cin >> coords;
    return 0;
}

CodePudding user response：

The correct syntax to create an object is:

coord = coordinates(ra, dec);

coord = coordinates{ra, dec};

(depending on your preferred style). This code constructs an object of type coordinates and then assigns it to the coord parameter.

CodePudding user response：

You can introduce a setter function for the coordinates class:

// inside the coordinates class definition
void set_coordinates(const std::vector<double>& ra, const std::vector<double>& dec)
{
    right_ascension = ra;
    declination = dec;
}

And then call it on the reference to an instance of the class in the overloaded input operator:

// ...in the operator>> definition
coord.set_coordinates(ra, dec);

Also, note that you'd better off define your default ctor like this:

coordinates() = default;

Among the reasons is that it uses vector's default ctor for the the right_ascension and the declination data members, which is what you want.