C++ Function Recursive version of function for x to the power n, n positive or negative

#include <iostream>
#include <iomanip>
double power(double x, int n);

int main()//from   w  ww . java 2  s . c  o  m
{
  for (int i {-3} ; i <= 3 ; ++i)           // Calculate powers of 8 from -3 to +3
    std::cout << std::setw(10) << power(8.0, i);

  std::cout << std::endl;
}

// Recursive function to calculate x to the power n
double power(double x, int n) {
    if (!n)
       return 1.0;                     // n zero

    if (n > 0)
       return x*power(x, n - 1);    // n positive

    return 1.0 / power(x, -n);              // n negative
}