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October 2023

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why diagnostic_information is std::exception::what: Unknown exception
by Bernard 30 Oct '23

30 Oct '23

greetings kind regards may i please inquire how not to obtain "std::exception::what: Unknown exception" from diagnosic_inforumation() . my meaning is to inquire how to obtain as per example on boost web page https://www.boost.org/doc/libs/1_83_0/libs/exception/doc/tutorial_diagnosti… output : "std::exception::what: example_io error" id est where did "example_io error" come from as neither boost::exception nor std:::exception accept constructor string arguments . please my code below . thank you kindly #include "stl" // #includes all stl #include files #include "boost\exception\all.hpp" using namespace std; struct ceXception : virtual boost::exception, virtual std::exception { using this_type = ceXception; ceXception() {} auto what() { cerr << __FUNCSIG__ << endl; return string("return from " + string(__FUNCSIG__)); } template<typename charType> friend std::basic_ostream<charType>& operator<<(std::basic_ostream<charType>& _ostream, const this_type&) { cerr << "to cerr from " << __FUNCSIG__ << endl; _ostream << "to ostream from " << __FUNCSIG__ << endl; return _ostream; } }; void foo() { try { BOOST_THROW_EXCEPTION(ceXception()); } catch (ceXception& e) { cerr << boost::diagnostic_information(e); } } int main() { foo(); return 0; }

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