example011.cpp

Data Abstraction & Problem Solving with C++源码

int main()
{
   int n = 5;
   double x = 2.0;

   // Computes n! for an integer n >= 0
   int f = 1;
   // Invariant: f == (j-1)!
   for (int j = 1; j <= n; ++j)
      f *= j;


   // Computes an approximation to e^x for a real x
   double t = 1.0;
   double s = 1.0;
   int    k = 1;

   // Invariant: t == x^(k-1)/(k-1)! and
   // s == 1+x+x^2 /2!+...+x^(k-1)/(k-1)!
   while (k <= n)
   {  t *= x/k;
      s += t;
      ++k;
   } // end while

   return 0;
}  // end main