ceph/src/boost/libs/math/example/nonfinite_facet_sstream.cpp

   1 // nonfinite_facet_sstream.cpp
   2
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE_1_0.txt
   5 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 // Copyright (c) 2006 Johan Rade
   8 // Copyright (c) 2011 Paul A. Bristow
   9
  10 /*!
  11 \file
  12 \brief Examples of nonfinite with output and input facets and stringstreams.
  13
  14 \detail Construct a new locale with the nonfinite_num_put and nonfinite_num_get
  15 facets and imbue istringstream, ostringstream and stringstreams,
  16 showing output and input (and loopback for the stringstream).
  17
  18 */
  19
  20 #include <boost/math/special_functions/nonfinite_num_facets.hpp>
  21 using boost::math::nonfinite_num_put;
  22 using boost::math::nonfinite_num_get;
  23
  24 using boost::math::legacy;
  25
  26 #include <iostream>
  27 using std::cout;
  28 using std::endl;
  29 #include <locale>
  30 using std::locale;
  31
  32 #include <sstream>
  33 using std::stringstream;
  34 using std::istringstream;
  35 using std::ostringstream;
  36
  37 #include <limits>
  38 using std::numeric_limits;
  39
  40 #include <assert.h>
  41
  42 int main()
  43 {
  44   //[nonfinite_facets_sstream_1
  45   locale old_locale;
  46   locale tmp_locale(old_locale, new nonfinite_num_put<char>);
  47   locale new_locale(tmp_locale, new nonfinite_num_get<char>);
  48   //] [/nonfinite_facets_sstream_1]
  49
  50   // Note that to add two facets,  nonfinite_num_put and nonfinite_num_get,
  51   // you have to add one at a time, using a temporary locale.
  52
  53   {
  54     ostringstream oss;
  55     oss.imbue(new_locale);
  56     double inf = numeric_limits<double>::infinity();
  57     oss << inf; // Write out.
  58     cout << "infinity output was " << oss.str() << endl;
  59     BOOST_MATH_ASSERT(oss.str() == "inf");
  60   }
  61   {
  62     istringstream iss;
  63     iss.str("inf");
  64     iss.imbue(new_locale);
  65     double inf;
  66     iss >> inf; // Read from "inf"
  67     cout << "Infinity input was " << iss.str() << endl;
  68     BOOST_MATH_ASSERT(inf == numeric_limits<double>::infinity());
  69   }
  70
  71   {
  72     //[nonfinite_facets_sstream_2
  73     stringstream ss;
  74     ss.imbue(new_locale);
  75     double inf = numeric_limits<double>::infinity();
  76     ss << inf; // Write out.
  77     BOOST_MATH_ASSERT(ss.str() == "inf");
  78     double r;
  79     ss >> r; // Read back in.
  80     BOOST_MATH_ASSERT(inf == r); // Confirms that the double values really are identical.
  81
  82     cout << "infinity output was " << ss.str() << endl;
  83     cout << "infinity input was " << r << endl;
  84     // But the string representation of r displayed will be the native type
  85     // because, when it was constructed, cout had NOT been imbued
  86     // with the new locale containing the nonfinite_numput facet.
  87     // So the cout output will be "1.#INF on MS platforms
  88     // and may be "inf" or other string representation on other platforms.
  89
  90     //] [/nonfinite_facets_sstream_2]
  91   }
  92
  93   {
  94     stringstream ss;
  95     ss.imbue(new_locale);
  96
  97     double nan = numeric_limits<double>::quiet_NaN();
  98     ss << nan; // Write out.
  99     BOOST_MATH_ASSERT(ss.str() == "nan");
 100
 101     double v;
 102     ss >> v; // Read back in.
 103
 104     cout << "NaN output was " << ss.str() << endl;
 105     cout << "NaN input was " << v << endl;
 106
 107     // assert(nan == v); // Always fails because NaN == NaN fails!
 108     // assert(nan == numeric_limits<double>::quiet_NaN()); asserts!
 109
 110     // And the string representation will be the native type
 111     // because cout has NOT been imbued with a locale containing
 112     // the nonfinite_numput facet.
 113     // So the output will be "1.#QNAN on MS platforms
 114     // and may be "nan" or other string representation on other platforms.
 115   }
 116
 117 } // int main()
 118
 119
 120 /*
 121 //[nonfinite_facet_sstream_output
 122
 123 infinity output was inf
 124 Infinity input was inf
 125 infinity output was inf
 126 infinity input was 1.#INF
 127 NaN output was nan
 128 NaN input was 1.#QNAN
 129
 130 //] [nonfinite_facet_sstream_output]
 131 */
 132