116 lines
3.6 KiB
C++
116 lines
3.6 KiB
C++
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/** nonfinite_num_facet_trap.cpp
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*
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* Copyright (c) 2012 Paul A. Bristow
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*
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt
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* or copy at http://www.boost.org/LICENSE_1_0.txt)
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*
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* This very simple program illustrates how to use the
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* `boost/math/nonfinite_num_facets.hpp` trapping output of infinity and/or NaNs.
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*
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\file
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\brief A very simple example of using non_finite_num facet for
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trapping output of infinity and/or NaNs.
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\note To actually get an exception throw by the iostream library
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one must enable exceptions.
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`oss.exceptions(std::ios_base::failbit | std::ios_base::badbit);`
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\note Which bit is set is implementation dependent, so enable exceptions for both.
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This is a fairly brutal method of catching nonfinites on output,
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but may suit some applications.
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*/
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#ifdef _MSC_VER
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# pragma warning(disable : 4127) // conditional expression is constant.
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// assumes C++ exceptions enabled /EHsc
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#endif
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#include <boost/cstdint.hpp>
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#include <boost/math/special_functions/nonfinite_num_facets.hpp>
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#include <iostream>
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#include <iomanip>
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using std::cout;
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using std::endl;
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using std::hex;
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#include <exception>
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#include <limits> // numeric_limits
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using std::numeric_limits;
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int main()
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{
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using namespace boost::math;
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std::cout << "nonfinite_num_facet_trap.cpp" << std::endl;
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const double inf = +std::numeric_limits<double>::infinity ();
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const double nan = +std::numeric_limits<double>::quiet_NaN ();
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{ // Output infinity and NaN with default flags (no trapping).
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std::ostringstream oss;
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std::locale default_locale (std::locale::classic ());
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std::locale C99_out_locale (default_locale, new boost::math::nonfinite_num_put<char>);
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oss.imbue (C99_out_locale);
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oss.exceptions(std::ios_base::failbit | std::ios_base::badbit);
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oss << inf << ' ' << nan;
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cout << "oss.rdstate() = " << hex << oss.rdstate() << endl; // 0
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cout << "os.str() = " << oss.str() << endl; // os.str() = inf nan
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}
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try
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{ // // Output infinity with flags set to trap and catch any infinity.
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std::ostringstream oss;
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std::locale default_locale (std::locale::classic ());
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std::locale C99_out_locale (default_locale, new boost::math::nonfinite_num_put<char>(trap_infinity));
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oss.imbue (C99_out_locale);
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oss.exceptions(std::ios_base::failbit | std::ios_base::badbit);
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// Note that which bit is set is implementation dependent, so enable exceptions for both.
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oss << inf;
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cout << "oss.rdstate() = " << hex << oss.rdstate() << endl;
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cout << "oss.str() = " << oss.str() << endl;
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}
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catch(const std::ios_base::failure& e)
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{ // Expect "Infinity".
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std::cout << "\n""Message from thrown exception was: " << e.what() << std::endl;
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}
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try
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{ // // Output NaN with flags set to catch any NaNs.
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std::ostringstream oss;
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std::locale default_locale (std::locale::classic ());
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std::locale C99_out_locale (default_locale, new boost::math::nonfinite_num_put<char>(trap_nan));
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oss.imbue (C99_out_locale);
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oss.exceptions(std::ios_base::failbit | std::ios_base::badbit);
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// Note that which bit is set is implementation dependent, so enable exceptions for both.
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oss << nan;
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cout << "oss.str() = " << oss.str() << endl;
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}
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catch(const std::ios_base::failure& e)
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{ // Expect "Infinity".
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std::cout << "\n""Message from thrown exception was: " << e.what() << std::endl;
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}
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return 0; // end of nonfinite_num_facet_trap.cpp
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} // int main()
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/*
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Output:
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nonfinite_num_facet_trap.cpp
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oss.rdstate() = 0
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os.str() = inf nan
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Message from thrown exception was: Infinity
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Message from thrown exception was: NaN
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*/
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