C / C++ / MFC

#define TEST_RANGE
#ifdef TEST_RANGE
#include <assert.h>
void minmax(const double newval, double&minv, double&maxv) {
   if (newval < minv)
      minv = newval;
   else if (newval > maxv)
      maxv = newval;
}
#endif
template <class basetype, class container_iterator>
basetype average(const container_iterator& start, const container_iterator& end) {
   basetype cumulated_average = 0;
   basetype cumulated_remainder = 0;
   basetype addendum = 0;
#ifdef TEST_RANGE
   double real_avg = 0.0;
   double val_min = *start;
   double val_max = *start;
   double avg_min = cumulated_average;
   double avg_max = cumulated_average;
   double rem_min = cumulated_remainder;
   double rem_max = cumulated_remainder;
#endif
   long long n_values = 0;
   for (auto pvalue = start; pvalue != end; ++pvalue) {
      ++n_values;
      addendum = cumulated_remainder - cumulated_average + *pvalue;
      cumulated_average += addendum/n_values;
      cumulated_remainder = addendum%n_values;
#ifdef TEST_RANGE
      real_avg += *pvalue;
      assert((char)(n_values*cumulated_average + cumulated_remainder - real_avg) == 0);
      minmax(*pvalue, val_min, val_max);
      minmax(cumulated_average, avg_min, avg_max);
      minmax(cumulated_remainder, rem_min, rem_max);
#endif
   }
#ifdef TEST_RANGE
   assert (fabs(n_values*cumulated_average - real_avg) < n_values);
   real_avg /= (double)n_values;
#endif
   return cumulated_average;
}
void test_average() {
   char cvalues[] = { 13,7,-27, 34, -3, 22, 33, -1, 18, 29,
                      13,7,-27, 34, -3, 22, 33, -1, 18, 29,
                      13,7,-27, 34, -3, 22, 33, -1, 18, 29,
                      13,7,-27, 34, -3, 22, 33, -1, 18, 29,
                      13,7,-27, 34, -3, 22, 33, -1, 18, 29
                    };
   auto cavg = average<char>(cvalues+0, cvalues+50);
}

Cum_avg(n) := sum(x1 ... xn) \ n
Cum_rem(n) := sum(x1 ... xn) % n

sum(x1...xn) = n*Cum_avg(n) + Cum_rem(n)

Cum_avg(n+1) := sum(x1...xn+1) \(n+1)
              = (sum(x1...xn)+xn+1) \(n+1)
              = (n*Cum_avg(n)+Cum_rem(n)+xn+1) \(n+1)
              = ((n+1)*Cum_avg(n)-Cum_avg(n)+Cum_rem(n)+xn+1) \(n+1)
              = Cum_avg(n) + (-Cum_avg(n)+Cum_rem(n)+xn+1) \(n+1)

Cum_rem(n+1) := addendum % (n+1)

Espen Harlinn wrote:

Normally you would create a class that is able to hold more than one configuration entry, and then something representing the various kinds of entries.

 

class ConfigEntry
{

};

class ConfigNode : public ConfigEntry
{
  typedef std::map<std::string,std::shared_ptr<ConfigEntry> > EntryMap;
  EntryMap entryMap_;

}; 

class ConfigValue : public ConfigEntry
{
};

class StringConfigValue : public ConfigValue
{
  std::string value_;
};

class IntConfigValue : public ConfigValue
{
  int value_;
};



class ConfigFile : public ConfigNode
{
};