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libs/math/example/nonfinite_loopback_ok.cpp

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+// 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)
+
+// Copyright (c) 2006 Johan Rade
+// Copyright (c) 2011 Paul A. Bristow
+
+/*!
+\file
+\brief Basic tests of nonfinite loopback.
+
+\detail Basic loopback test outputs using nonfinite facets
+(output and input) and reads back in, and checks if loopback OK.
+
+Expected to work portably on all platforms.
+
+*/
+
+#ifdef _MSC_VER
+#   pragma warning(disable : 4702)
+#   pragma warning(disable : 4127) // conditional expression is constant.
+#endif
+
+#include <boost/math/special_functions/nonfinite_num_facets.hpp>
+using boost::math::nonfinite_num_get;
+using boost::math::nonfinite_num_put;
+
+#include <iostream>
+using std::cout;
+using std::endl;
+
+#include <locale>
+using std::locale;
+
+#include <sstream>
+using std::stringstream;
+#include <limits>
+using std::numeric_limits;
+
+#include <assert.h>
+
+int main()
+{
+
+  if((std::numeric_limits<double>::has_infinity == false) || (std::numeric_limits<double>::infinity() == 0))
+  {
+    std::cout << "Infinity not supported on this platform." << std::endl;
+    return 0;
+  }
+
+  if((std::numeric_limits<double>::has_quiet_NaN == false) || (std::numeric_limits<double>::quiet_NaN() == 0))
+  {
+    std::cout << "NaN not supported on this platform." << std::endl;
+    return 0;
+  }
+  //locale old_locale; // Current global locale.
+  // Create tmp_locale and store the output nonfinite_num_put facet in it.
+  //locale tmp_locale(old_locale, new nonfinite_num_put<char>);
+  // Create new_locale and store the input nonfinite_num_get facet in it.
+  //locale new_locale(tmp_locale, new nonfinite_num_get<char>);
+  // Can only add one facet at a time, hence need a tmp_locale.
+  // Unless we write:
+
+  std::locale new_locale(std::locale(std::locale(std::locale(),
+    new boost::math::nonfinite_num_put<char>),
+    new boost::math::nonfinite_num_get<char>));
+  
+  stringstream ss; // Both input and output, so need both get and put facets.
+  
+  ss.imbue(new_locale);
+
+  double inf = numeric_limits<double>::infinity();
+  ss << inf; // Write out.
+  double r;
+  ss >> r; // Read back in.
+
+  assert(inf == r); // OK MSVC <= 10.0!
+
+} // int main()
+
+/*
+
+Output:
+
+nonfinite_loopback_ok.vcxproj -> J:\Cpp\fp_facet\fp_facet\Debug\nonfinite_loopback_ok.exe
+
+*/
+
+