C++ Primer 7.7

7.7.cpp

#include <iostream>
const int Max = 5;

// function prototypes
double * fill_array(double ar[], int limit);
void show_array(const double ar[], double * n);
void revalue(double r, double ar[], double * n);

int main()
{
  using namespace std;
  double properties[Max];

  double * pointer = fill_array(properties, Max);
  show_array(properties, pointer);

  cout << "Enter revaluation factor: ";
  double factor;
  cin >> factor;
  revalue(factor, properties, pointer);
  show_array(properties, pointer);
  cout << "Done.\n";

  return 0;
}

double * fill_array(double ar[], int limit)
{
  using namespace std;
  double temp;
  int i;
  for (i = 0; i < limit; i++) {
    cout << "Enter value #" << (i + 1) << ": ";
    cin >> temp;
    if (!cin) { // bad input
      cin.clear();
      while (cin.get() != '\n') {
        continue;
      }
      cout << "Bad input; input process terminated.\n";
      break;
    } else if (temp < 0) { // signal to terminate
      break;
    }
    ar[i] = temp;
  }
  if (0 == i) {
    exit(-1);
  }

  return &ar[i - 1];
}

// the following function can use, but not alter,
// the array whose address is ar
void show_array(const double ar[], double * n)
{
  using namespace std;

  for (int i = 0; ; i++) {
    cout << "Property #" << (i + 1) << ": $";
    cout << ar[i] << endl;
    if (n == &ar[i]) { break; }
  }
}

// multiplies each element of ar[] by r
void revalue(double r, double ar[], double * n)
{
  for (int i = 0; ; i++) {
    ar[i] *= r;
    if (&ar[i] == n) { break; }
  }
}