ex5_14.cpp

Visual C++ 2005的源代码

// Ex5_14.cpp (based on Ex5_01.cpp)
// A recursive version of x to the power n
#include <iostream>
using std::cout;
using std::endl;

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

int main(void)
{
  double x = 2.0;                // Different x from that in function power
  double result = 0.0;

  // Calculate x raised to powers -3 to +3 inclusive
  for(int index = -3 ; index<=3 ; index++)
  cout << x << " to the power " << index << " is " << power(x, index)<< endl;

   return 0;
}
// Recursive function to compute integral powers of a double value
// First argument is value, second argument is power index
double power(double x, int n)
{
   if(n < 0)
   {
      x = 1.0/x;
      n = -n;
   }
   if(n > 0)
      return x*power(x, n-1);
   else
      return 1.0;
}