pointers-and-refs-struct.cpp

#include <iostream>
using namespace std;

struct Foo{
  int a;
  char b;
};

int main(void){
  Foo x = {42, 'x'};
  cout << "Foo x is (" << x.a << ", " << x.b << ") ";
  cout << "and it is located at " << &x << endl;
  cout << endl;

  Foo* p = &x;
  cout << "Let's set Foo* p equal to the address of x..." << endl;
  cout << "Foo *p is " << p << " and it is located at " << &p << endl;
  // Can't say this cout << "By dereferencing p, p points to " << *p << endl;
  cout << "By dereferencing the parts of p using the -> operator" << endl;
  cout << "p->a is " << p->a << endl;
  cout << "and p-> is " << p->b << endl;
  cout << endl;

  Foo& r = x;
  cout << "Let's set Foo& r equal to x..." << endl;
  cout << "Foo& r is (" << r.a << ", " << r.b << ") and it is located at " << &r << endl;
  cout << "Notice that r (" << &r << ") has the same address as x (" << &x << ")" << endl;
  cout << "This is very strange since x and r are two different things." << endl;
  cout << endl;

  cout << "Let's set p equal to the address of r..." << endl;
  p = &r;
  cout << "Foo *p is " << p << " and it is located at " << &p << endl;
  //Can't say this cout << "By dereferencing p, p points to " << *p << endl;
  cout << "By dereferencing the parts of p using the -> operator" << endl;
  cout << "p->a is " << p->a << endl;
  cout << "and p-> is " << p->b << endl;
  cout << endl;

  cout << endl;
  Foo y = {17, 'z'};
  cout << "Foo y is (" << y.a << ", " << y.b << ") ";
  cout << "and it is located at " << &y << endl;
  cout << endl;

  cout << "Can I have p point to y?" << endl;
  p = &y;
  cout << "Foo *p is " << p << " and it is located at " << &p << endl;
  //cout << "By  dereferencing p, p points to " << *p << endl;
  cout << "By dereferencing the parts of p using the -> operator" << endl;
  cout << "p->a is " << p->a << endl;
  cout << "and p-> is " << p->b << endl;
  cout << "The answer is yes I can!" << endl;
  cout << endl;

  cout << "Can I have r bind to y?" << endl;
  r = y;
  cout << "Let's set Foo& r equal to y..." << endl;
  cout << "Foo& r is (" << r.a << ", " << r.b << ") and it is located at " << &r << endl;
  cout << "Notice that r (" << &r << ") has the same address as x (" << &x << ") still!!!!" << endl;
  cout << "What just happened? (You can't rebind a reference.)" << endl;
  cout << "Foo x was changed to be equal to Foo y." << endl;
  cout << "Foo x is (" << x.a << ", " << x.b << ") ";
    cout << "and it is located at " << &x << endl;
  cout << "Foo y is (" << y.a << ", " << y.b << ") ";
  cout << "and it is located at " << &y << endl;

  return 0;
}