multiprecision/example/cpp_bin_float_import_export.cpp

50 lines
1.3 KiB
C++

///////////////////////////////////////////////////////////////
// Copyright 2015 John Maddock. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
#include <boost/multiprecision/cpp_bin_float.hpp>
#include <iostream>
#include <iomanip>
#include <vector>
#include <iterator>
// Contains Quickbook snippets in comments.
//[IE2
/*`
Importing or exporting cpp_bin_float is similar, but we must procede via an intermediate integer:
*/
/*=
#include <boost/multiprecision/cpp_bin_float.hpp>
#include <iostream>
#include <iomanip>
#include <vector>
#include <iterator>
*/
int main()
{
using boost::multiprecision::cpp_bin_float_100;
using boost::multiprecision::cpp_int;
// Create a cpp_bin_float to import/export:
cpp_bin_float_100 f(1);
f /= 3;
// export into 8-bit unsigned values, most significant bit first:
std::vector<unsigned char> v;
export_bits(cpp_int(f.backend().bits()), std::back_inserter(v), 8);
// Grab the exponent as well:
int e = f.backend().exponent();
// Import back again, and check for equality, we have to procede via
// an intermediate integer:
cpp_int i;
import_bits(i, v.begin(), v.end());
cpp_bin_float_100 g(i);
g.backend().exponent() = e;
BOOST_ASSERT(f == g);
}
//]