Check whether xy-aligned rectangle r1 and r2 intersects. If it is, return the intersected range.

rect_intersect.cc

#include <iostream>
using namespace std;

struct Rectangle {
    int x, y, width, height;
};

bool is_intersect(const Rectangle &r1, const Rectangle &r2);

Rectangle rect_intersect(const Rectangle &r1, const Rectangle &r2)
{
    if (is_intersect(r1, r2)) {
        return {std::max(r1.x, r2.x), std::max(r1.y, r2.y),
                std::min(r1.x + r1.width, r2.x + r2.width) - std::max(r1.x, r2.x),
                std::min(r1.y, r2.y) - std::max(r1.y - r1.height, r2.y - r2.height)};
    } else {
        return {0, 0, -1, -1};
    }
}

// determine whether a rectangle is NOT overlap over another
bool is_intersect(const Rectangle &r1, const Rectangle &r2)
{
    return !(r1.x + r1.width < r2.x || r2.x + r2.width < r1.x ||
           r1.y - r1.height > r2.y || r2.y - r2.height > r1.y);
}

int main()
{
    Rectangle r1 = {0, 4, 3, 4}, r2 = {2, 5, 4, 5};
    Rectangle inter = rect_intersect(r1, r2);
    cout << inter.x << " " << inter.y << " " << inter.width << " " << inter.height << endl;
    return 0;
}