spirit/test/karma/regression_real_scientific.cpp

41 lines
1.2 KiB
C++

// Copyright (c) 2010 Lars Kielhorn
// Copyright (c) 2001-2010 Hartmut Kaiser
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#include <boost/config/warning_disable.hpp>
#include <boost/detail/lightweight_test.hpp>
#include <boost/spirit/include/karma.hpp>
#include <iostream>
#include <string>
#include <iterator>
namespace karma = boost::spirit::karma;
// define a new real number formatting policy
template <typename Num>
struct scientific_policy : karma::real_policies<Num>
{
// we want the numbers always to be in scientific format
static int floatfield(Num) { return std::ios_base::scientific; }
};
int main()
{
// define a new generator type based on the new policy
typedef karma::real_generator<double, scientific_policy<double> >
science_type;
science_type const scientific = science_type();
std::string output;
typedef std::back_insert_iterator<std::string> output_iterator;
output_iterator sink(output);
// should output: 1.0e-01, but will output: 10.0e-02
BOOST_TEST(karma::generate(sink, scientific, 0.1) && output == "1.0e-01");
return boost::report_errors();
}