29785

how to catch a general exception and show its derived what()

The problem happens with code like this:

#include <cstdlib> #include <iostream> #include <stdexcept> using namespace std; int main(int argc, char** argv) { try { throw runtime_error("Message"); } catch (exception e) { cout << e.what(); } return 0; }

I expect Message to appear. But the result was std::exception. I thought the subclass virtual functions can be called from the superclass reference. How can fix that?

Answer1:

C++ makes an explicit distinction between reference and value copy. Use

catch (const std::exception& e)

to catch by reference instead of value.

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