[C++] Basic Collision Detection

#include <iostream>
#include <math.h>
#include <stdlib.h>

using namespace std;

struct Circle {
  int x;
  int y;
  int radius;
};

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

bool CirclesCollision(Circle circle1, Circle circle2);
bool RectangleCircleCollision(Circle circle1, Rectangle rectangle1);
void createBoundingBox(Circle circle1);

int main() {

  Circle circle1;
//  Circle circle2;

  Rectangle rectangle1;

  cout << "Enter circle1's center X:";
  cin >> circle1.x;
  cout << "Enter circle1's center Y:";
  cin >> circle1.y;
  cout << "Enter circle1's radius:";
  cin >> circle1.radius;
/*
  cout << "Enter circle2's center X:";
  cin >> circle2.x;
  cout << "Enter circle2's center Y:";
  cin >> circle2.y;
  cout << "Enter circle2's radius:";
  cin >> circle2.radius;
*/
  cout << "Enter rectangle1's center X:";
  cin >> rectangle1.x;
  cout << "Enter rectangle1's center Y:";
  cin >> rectangle1.y;
  cout << "Enter rectangle1's width:";
  cin >> rectangle1.width;
  cout << "Enter rectangle1's height:";
  cin >> rectangle1.height;

  //cout << (CirclesCollision(circle1, circle2) ? "Circles Collision detected!" : "No collision detected!");
  cout << (RectangleCircleCollision(circle1, rectangle1) ? "\nRectangle <-> Circle Collision detected!" : "\nNo collision detected!");

  createBoundingBox(circle1);

  return 0;
}

bool CirclesCollision(Circle circle1, Circle circle2) {
  int x_axis = circle1.x - circle2.x;
  int y_axis = circle1.y - circle2.y;
  int dist = sqrt((x_axis * x_axis) + (y_axis * y_axis));

  return dist < circle1.radius + circle2.radius ? true : false;
}
/*
bool RectangleCircleCollision(Circle circle1, Rectangle rectangle1) {
  int dist_x = abs(circle1.x - rectangle1.x);
  int dist_y = abs(circle1.y - rectangle1.y);

  if (dist_x > (rectangle1.width / 2 + circle1.radius))
    return false;

  if(dist_y > (rectangle1.height / 2 + circle1.radius))
    return false;

  if(dist_x <= (rectangle1.width / 2))
    return true;

  if(dist_y <= (rectangle1.height / 2))
    return true;

  int dest_x = dist_x - rectangle1.width / 2;
  int dest_y = dist_y - rectangle1.height / 2;

  return (dest_x * dest_x + dest_y * dest_y <= (circle1.radius * circle1.radius));
}*/

bool RectangleCircleCollision(Circle circle1, Rectangle rectangle1) {
  int half_x = (rectangle1.width / 2);
  int half_y = (rectangle1.height / 2);

  int center_x = (circle1.x - (rectangle1.x + half_x));
  int center_y = (circle1.y - (rectangle1.y + half_y));

  int side_x = (abs(center_x) - half_x);
  int side_y = (abs(center_y) - half_y);

  if(side_x > circle1.radius || side_y > circle1.radius) // outside
    return false;
  if(side_x < -circle1.radius && side_y < -circle1.radius) // inside
    return true;
  if(side_x < 0 || side_y < 0) // sidecorner
    return true;

  return side_x * side_x + side_y * side_y < circle1.radius * circle1.radius;
}

void createBoundingBox(Circle circle1) {
    int dy1 = circle1.y + circle1.radius;
    int dy2 = circle1.y - circle1.radius;

    int dx1 = circle1.x - circle1.radius;
    int dx2 = circle1.x + circle1.radius;

    int x1 = (dy1 + dx1) - circle1.radius;
    int x2 = (dy1 + dx2) - circle1.radius;
    int x3 = (dy2 + dx2) + circle1.radius;
    int x4 = (dy2 + dx1) + circle1.radius;

    cout << "\nCoordinates of the upper left corner of the box: (x: " << x1 << " y: " << dy1 << ")" << endl;
    cout << "\nCoordinates of the upper right corner of the box: (x: " << x2 << " y: " << dy1 << ")" << endl;
    cout << "\nCoordinates of the lower right corner of the box: (x: " << x3 << " y: " << dy2 << ")" << endl;
    cout << "\nCoordinates of the lower left corner of the box: (x: " << x4 << " y: " << dy2 << ")" << endl;
}