Function power

Exercises/Modules/Chapter 08/Soln8_08.cpp:17–26

Recursive function to calculate x to the power n

// Recursive function to calculate x to the power n
long double power(double x, int n)
{
  if (n == 0)     return 1.0;
  else if (n < 0) return 1.0 / power(x, -n);
  else if (n % 2) return x * power(x, n - 1);     // n is odd
  
  // If we make it this far, n > 0 and even
  const auto y{ power(x, n / 2) };
  return y * y;
}