#include <iostream>
using namespace std;
struct Point {
double x;
double y;
};
// pass by reference - the function is modifying p
void scale_point(Point &p, double scaling_factor) {
p.x = p.x * scaling_factor;
p.y = p.y * scaling_factor;
}
// pass by const reference - the function is not modifying p
void print_point(const string &prefix, const Point &p) {
cout << prefix << '(' << p.x << ',' << p.y << ')' << endl;
}
// pass by const reference - the function is not modifying p1, p2
Point subtract_points(const Point &p1, const Point &p2) {
Point delta;
delta.x = p1.x - p2.x;
delta.y = p1.y - p2.y;
return delta;
}
int main() {
Point p1;
Point p2;
p1.x = 1;
p1.y = 2;
p2.x = 3;
p2.y = 3;
print_point("first point: ", p1);
print_point("second point: ", p2);
print_point("delta: ", subtract_points(p1, p2));
// scale second point by a factor of 2
cout << endl << "scaling the 2nd point to 2x" << endl;
scale_point(p2, 2);
print_point("first point: ", p1);
print_point("second point: ", p2);
print_point("delta:", subtract_points(p1, p2));
return 0;
