How come this code snippet did not need to be passed by reference or by address? Please explain these concepts in detail regarding objects.

1// example: one class, two objects 2#include rect area: 12 rectb area: 30 using namespace std 5 class Rectangle ( int width, height; 7public: void set values (int,int); int area freturn width*height;) 10 12 void Rectangle::set values (int x, int y) 13 width; 14 height-Y: 15 h 16 17int main ) 18 Rectangle rect, rectb; 19 rect.set values (3,4) 20 rectb.set values (5,6); 21 cout