Create a sum of two Array instances - c++

Question

The essence of what I want to do is to take two instances of Vector2D and create a third vector that is to be returned and made into the third instance. The problem I am facing is that I am not entirely sure on how to go ahead in doing so. I have tried to find the syntax for sending in instances, if there is such a one, but I have not managed to find anything useful in any of my books.
#include<iostream>
#include<string>
#include<array>
using namespace std;
class vector2D
{
public:
array<float, 2> get()
{
return xy_coord;
}
void set(float x, float y)
{
xy_coord[0] = x;
xy_coord[1] = y;
}
array<float, 2> vectorAdd(a, b)
{
array<float, 2> c;
for (int i = 0; i < 2; i++)
{
c[i] = a[i] + b[i];
}
return c;
}
private:
array<float, 2> xy_coord;
};
int main()
{
string y;
vector2D a, b, c;
array<float, 2> temp;
a.set(2.0, 3.0);
b.set(4.0, 5.0);
temp = c.vectorAdd(a, b);
c.set(temp[0], temp[1]);
getline(cin, y);
}
The idea is to send in the instances a and b to vectorAdd and sum them up and then set c equal to the returned value (I am sure there is a better way to write the code in the main(), but I am not sure how). In short, what would a and b need to be defined as to make this work, assuming it can work at all.

Answer 1

Maybe you could do something like this instead, so you don't have to pass array around:
#include <iostream>
class Vector2D
{
private:
double _x;
double _y;
public:
Vector2D() = delete;
Vector2D(double x, double y) : _x(x), _y(y) {}
double X() const { return _x; }
double Y() const { return _y; }
Vector2D operator+(Vector2D const &v) const
{
return Vector2D(X() + v.X(), Y() + v.Y());
}
};
int main()
{
Vector2D v1(10.0, 20.0);
Vector2D v2(100.0, 200.0);
Vector2D v3 = v1 + v2;
std::cout << v3.X() << " " << v3.Y();
return 0;
}
Prints:
110 220

Answer 2

Do you need to use array<float, 2>? Have you thought of using pair<float, float>?
A lot (all?) of the operations that you have in your Vector2D class come for free with Pair<>.
Then you just create operator+ as others have suggested.
#include <iostream>
#include <utility>
using namespace std;
using Coord = pair<float, float>;
template <typename L, typename R>
Coord operator+(const L& x, const R& y) { return std::make_pair(x.first + y.first, x.second + y.second); }
int main()
{
Coord a { 5.0f, 6.0f };
Coord b { 7.0f, 9.0f };
Coord c = a + b;
std::cout.precision(5);
std::cout << "c= (" << std::fixed << c.first << ", " << c.second << ")" << std::endl;
return 0;
}