Exception not caught in try catch block

问题

I do a simple throw "TEST THROW" and it isn't caught in my catch (std::exception& e). Is it because I'm catching an std::exception& e? I mean, are only exception classes derived from std::exception caught? If not, am I doing something wrong or is it normal? By the way, none of the two catch blocks caught the throw exception.

int main()
{
try
{
    throw "TEST THROW"; // TEST
    Core core;

    core.Init();
    core.Load();

    while (!core.requestCloseWindow)
    {
        core.HandleInput();

        core.Update();
        core.Draw();
    }

    core.Unload();
    core.window->close();
}
catch (std::exception& e)
{
    std::cerr << e.what() << std::endl;
    try
    {
        time_t rawTime;
        struct tm* timeInfo;
        char timeBuffer [80];

        time(&rawTime);
        timeInfo = localtime(&rawTime);

        strftime(timeBuffer, 80, "%F %T", timeInfo);
        puts(timeBuffer);

        std::ofstream ofs; // Pas besoin de close, car le destructeur le fait.
        ofs.exceptions(std::ofstream::failbit | std::ofstream::badbit);
        ofs.open("log.txt", std::ofstream::out | std::ofstream::app);
        ofs << e.what() << std::endl;
    }
    catch (std::exception& e)
    {
        std::cerr << "An error occured while writing to a log file!" << std::endl;
    }
}

return 0;

}

回答1:

You're throwing a const char*. std::exception only catches std::exception and all derived classes of it. So in order to catch your throw, you should throw std::runtime_error("TEST THROW") instead. Or std::logic_error("TEST THROW"); whatever fits better. The derived classes of std::exception are listed here.

回答2:

Another reason people may hit this issue, especially if they've been writing Java recently, is that they may be throwing a pointer to the exception.

/* WARNING WARNING THIS CODE IS WRONG DO NOT COPY */
try {
    throw new std::runtime_error("catch me");
} catch (std::runtime_error &err) {
    std::cerr << "exception caught and ignored: " << err.what() << std::end;
}
/* WARNING WARNING THIS CODE IS WRONG DO NOT COPY */

will not catch the std::runtime_error* you threw. It'll probably die with a call to std::terminate for the uncaught exception.

Don't allocate the exception with new, just throw the constructor by-value, e.g.

try {
    /* note: no 'new' here */
    throw std::runtime_error("catch me");
} catch (std::runtime_error &err) {
    std::cerr << "exception caught and ignored: " << err.what() << std::end;
}

回答3:

This also may happen when you throw an exception of a an inherted type but the inhertence is private

回答4:

You can add a catch (...) block to get it.

回答5:

Since this is not a MCVE (what is Core?), I can't address explicitly the problem, but you are surely missing to

#include <exception>

Actually, GCC compiles even without the inclusion, but exception won't be caught and you will end up with

terminate called after throwing an instance of 'std::exception'

what(): std::exception

./{program}: {PID} Aborted (core dumped)

来源：https://stackoverflow.com/questions/30560422/exception-not-caught-in-try-catch-block

标签

c++

exception