#include <iostream>
#include <string>
#include <boost/lexical_cast.hpp>

//From http://www.richelbilderbeek.nl/CppAskUserForDouble.htm
const double AskUserForDouble()
{
  while (1)
  {
    const std::string s = AskUserForString();
    if (IsDouble(s)==false) continue;
    return boost::lexical_cast<double>(s);
  }
}