#include <iostream>

using namespace std;

struct array_of_four
{ int v1, v2, v3, v4; };    // v1 is supposed to represent A[0], v2 is A[1], v3 is A[2], v4 is A[3]

int & access(array_of_four & A, int pos)
{ if (pos < 0 || pos > 3)
  { cout << "Index to array_of_four is out of bounds\n";
    exit(1); }
  if (pos == 0)
    return A.v1;
  if (pos == 1)
    return A.v2;
  if (pos == 2)
    return A.v3;
  return A.v4; }

int main()
{ int a = 111, b = 222, c = 333, d = 444, e = 555, f = 666;
  array_of_four R;
  int z = 11, y = 22, x = 33, w = 44, v = 55, u = 66, t = 77;
  int start, stop;

  cout << "\nVariables before accessing the array:\n";
  cout << "  a = " << a << "\n";
  cout << "  b = " << b << "\n";
  cout << "  c = " << c << "\n";
  cout << "  d = " << d << "\n";
  cout << "  e = " << e << "\n";
  cout << "  f = " << f << "\n";
  cout << "  z = " << z << "\n";
  cout << "  y = " << y << "\n";
  cout << "  x = " << x << "\n";
  cout << "  w = " << w << "\n";
  cout << "  v = " << v << "\n";
  cout << "  u = " << u << "\n";
  cout << "  t = " << t << "\n";

  /* this represents a really big computation that went wrong */
  start = 0; stop = 3;

  for (int i = start; i <= stop; i += 1)
    access(R, i) = 1000 + i;
  /* pretend to use the array here */

  cout << "The array conatins:\n";
  cout << "  R[0] = " << access(R, 0) << "\n";
  cout << "  R[1] = " << access(R, 1) << "\n";
  cout << "  R[2] = " << access(R, 2) << "\n";
  cout << "  R[3] = " << access(R, 3) << "\n";
  cout << "\nVariables after accessing the array:\n";
  cout << "  a = " << a << "\n";
  cout << "  b = " << b << "\n";
  cout << "  c = " << c << "\n";
  cout << "  d = " << d << "\n";
  cout << "  e = " << e << "\n";
  cout << "  f = " << f << "\n";
  cout << "  z = " << z << "\n";
  cout << "  y = " << y << "\n";
  cout << "  x = " << x << "\n";
  cout << "  w = " << w << "\n";
  cout << "  v = " << v << "\n";
  cout << "  u = " << u << "\n";
  cout << "  t = " << t << "\n";
}