13 Vector2D(
float x,
float y);
15 friend Vector2D& operator+(Vector2D& vector1,
const Vector2D& vector2);
16 friend Vector2D& operator-(Vector2D& vector1,
const Vector2D& vector2);
17 friend Vector2D& operator*(Vector2D& vector1,
const Vector2D& vector2);
18 friend Vector2D& operator/(Vector2D& vector1,
const Vector2D& vector2);
19 friend Vector2D& operator+=(Vector2D& vector1,
const Vector2D& vector2);
21 Vector2D& operator*(
const int& i);