// Ex5_01.cpp
// Declaring, defining, and using a function
#include <iostream>
using std::cout;
using std::endl;

double power(double x, int n);    // Function prototype

int main()
{
  int index { 3 };                 // Raise to this power
  double x { 3.0 };                // Different x from that in function power
  double y {};

  y = power(5.0, 3);               // Passing constants as arguments
 cout << endl << "5.0 cubed = " << y;

 cout << endl << "3.0 cubed = "
      << power(3.0, index);        // Outputting return value

 x = power(x, power(2.0, 2.0));    // Using a function as an argument
 cout << endl                      // with auto conversion of 2nd parameter
      << "x = " << x;

  cout << endl;
  return 0;
}

// Function to compute positive integral powers of a double value
// First argument is value, second argument is power index
double power(double x, int n)
{
  // Function body starts here...
  double result { 1.0 };           // Result stored here
  for (int i {1}; i <= n; i++)
    result *= x;
  return result;
}                                  // ...and ends here