ceph/src/boost/libs/multiprecision/example/cpp_bin_float_import_export.cpp

   1 ///////////////////////////////////////////////////////////////
   2 //  Copyright 2015 John Maddock. Distributed under the Boost
   3 //  Software License, Version 1.0. (See accompanying file
   4 //  LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
   5
   6 #include <boost/multiprecision/cpp_bin_float.hpp>
   7 #include <iostream>
   8 #include <iomanip>
   9 #include <vector>
  10 #include <iterator>
  11
  12 // Contains Quickbook snippets in comments.
  13
  14 //[IE2
  15
  16 /*`
  17 Importing or exporting cpp_bin_float is similar, but we must procede via an intermediate integer:
  18 */
  19 /*=
  20 #include <boost/multiprecision/cpp_bin_float.hpp>
  21 #include <iostream>
  22 #include <iomanip>
  23 #include <vector>
  24 #include <iterator>
  25 */
  26
  27 int main()
  28 {
  29    using boost::multiprecision::cpp_bin_float_100;
  30    using boost::multiprecision::cpp_int;
  31    // Create a cpp_bin_float to import/export:
  32    cpp_bin_float_100 f(1);
  33    f /= 3;
  34    // export into 8-bit unsigned values, most significant bit first:
  35    std::vector<unsigned char> v;
  36    export_bits(cpp_int(f.backend().bits()), std::back_inserter(v), 8);
  37    // Grab the exponent as well:
  38    int e = f.backend().exponent();
  39    // Import back again, and check for equality, we have to procede via
  40    // an intermediate integer:
  41    cpp_int i;
  42    import_bits(i, v.begin(), v.end());
  43    cpp_bin_float_100 g(i);
  44    g.backend().exponent() = e;
  45    BOOST_ASSERT(f == g);
  46 }
  47
  48 //]
  49