Vector3D - CPP

// Vector3D.h
#ifndef __Vector3D
#define __Vector3D

class Vector3D
{
private:
    double x, y, z;

public:
    Vector3D(double x = 0, double y = 0, double z = 0)
    {
        this->x = x;
        this->y = y;
        this->z = z;
    }

    double getX() { return x; }
    void setX(double value) { x = value; }

    double getY() { return y; }
    void setY(double value) { y = value; }

    double getZ() { return z; }
    void setZ(double value) { z = value; }

    friend Vector3D operator+(const Vector3D &v1, const Vector3D &v2);

    Vector3D& operator+=(const Vector3D &v) {
        this->x += v.x;
        this->y += v.y;
        this->z += v.z;

        return *this;
    }
};

inline Vector3D operator+(const Vector3D &v1, const Vector3D &v2) {
    return Vector3D(v1.x + v2.x, v1.y + v2.y, v1.z + v2.z);
}

#endif // !__Vector3D

// Vector3D.cpp
#include <stdlib.h>
#include "Vector3D.h"

using namespace std;

int main() {
    Vector3D vec1(1, 2, 4);
    Vector3D vec2(3, 5, 7);

    Vector3D vec3 = vec1 + vec2;

    system("pause");
    return 0;
}