Ticket #8065: MPRoundingBug.cpp

#include <iostream>
#include <Windows.h>
#include <boost/math/special_functions/round.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>

namespace mp = boost::multiprecision;

template<int N>
void roundTest()
{
  typedef mp::number<mp::cpp_dec_float<N>, mp::et_off> decimal;

  const decimal origDigs(1.0);
  const decimal scale = pow(decimal(10), N);
  decimal digs = origDigs * scale;
  digs = boost::math::round(digs );
  digs = digs / scale;

  std::string result = digs.str();
  if (result != origDigs.str())
  {
    std::cout << "roundTest failed for N = " << N << ": " << result << std::endl;
  }
}

template<int N>
struct roundTester
{
  static void test ()
  {
    roundTest<N>();
    roundTester<N-1>::test();
  }
};

template<>
struct roundTester<0>
{
  static void test ()
  {
    roundTest<0>();
  }
};

int main(int argc, char* argv[])
{
  roundTester<60>::test();
  return 0;
}