Parameters passing - Call by adress structure

#include <iostream>
#include <string>
using namespace std;
struct Rectangle
{
    int length;
    int breadth;

};
void changeLength( struct Rectangle *p, int l)
{
    p->length = l;
}
int main()
{
    struct Rectangle r = {10,20};
    changeLength(&r, 20);
    cout << r.length << endl;
}