Question

我不希望我的程序崩溃，所以我用SEH启用了C ++异常。所以，如果有一些错误，即NULL指针访问发生，我的程序可以用catch（...）捕获它。

我想知道： 1.使用SEH启用C ++异常有什么缺点吗？ 2.如果被catch（...）捕获，我怎么能知道异常细节？

Answer 1

据我所知，没有性能上的缺点，因为我非常确定C ++异常是通过SEH实现的。您所做的只是启用扩展程序以获取操作系统级别的异常。然而，有一个主要的缺点，有两个涉及。
您通常使用__try和__except来捕获SEH例外情况; more information here。请注意，这是缺点：以这种方式捕获的异常不会运行析构函数。但是，您可以使用函数_set_se_translator将SEH异常转换为C ++异常。

以下是我的一个项目（在MSVC 2010中使用Boost和C ++ 0x）：

bool ignore_exception(unsigned pCode)
{
    const unsigned ignoreList[] = {EXCEPTION_BREAKPOINT,
        EXCEPTION_FLT_DENORMAL_OPERAND, EXCEPTION_FLT_DIVIDE_BY_ZERO,
        EXCEPTION_FLT_INEXACT_RESULT, EXCEPTION_FLT_OVERFLOW, EXCEPTION_FLT_UNDERFLOW,
        EXCEPTION_INT_OVERFLOW, EXCEPTION_SINGLE_STEP};

    auto result = std::search_n(std::begin(ignoreList), std::end(ignoreList),
                    1, pCode);
    return result != std::end(ignoreList);              
}

std::string code_string(unsigned pCode)
{
    switch (pCode)
    {
    case EXCEPTION_ACCESS_VIOLATION:
        return "Access violation";
    case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
        return "Out of array bounds";
    case EXCEPTION_BREAKPOINT:
        return "Breakpoint";
    case EXCEPTION_DATATYPE_MISALIGNMENT:
        return "Misaligned data";
    case EXCEPTION_FLT_DENORMAL_OPERAND:
        return "Denormalized floating-point value";
    case EXCEPTION_FLT_DIVIDE_BY_ZERO:
        return "Floating-point divide-by-zero";
    case EXCEPTION_FLT_INEXACT_RESULT:
        return "Inexact floating-point value";
    case EXCEPTION_FLT_INVALID_OPERATION:
        return "Invalid floating-point operation";
    case EXCEPTION_FLT_OVERFLOW:
        return "Floating-point overflow";
    case EXCEPTION_FLT_STACK_CHECK:
        return "Floating-point stack overflow";
    case EXCEPTION_FLT_UNDERFLOW:
        return "Floating-point underflow";
    case EXCEPTION_GUARD_PAGE:
        return "Page-guard access";
    case EXCEPTION_ILLEGAL_INSTRUCTION:
        return "Illegal instruction";
    case EXCEPTION_IN_PAGE_ERROR:
        return "Invalid page access";
    case EXCEPTION_INT_DIVIDE_BY_ZERO:
        return "Integer divide-by-zero";
    case EXCEPTION_INT_OVERFLOW:
        return "Integer overflow";
    case EXCEPTION_INVALID_DISPOSITION:
        return "Invalid exception dispatcher";
    case EXCEPTION_INVALID_HANDLE:
        return "Invalid handle";
    case EXCEPTION_NONCONTINUABLE_EXCEPTION:
        return "Non-continuable exception";
    case EXCEPTION_PRIV_INSTRUCTION:
        return "Invalid instruction";
    case EXCEPTION_SINGLE_STEP:
        return "Single instruction step";
    case EXCEPTION_STACK_OVERFLOW:
        return "Stack overflow";
    default:
        return "Unknown exception";
    }
}

void stack_fail_thread()
{
    std::cerr << "Unhandled exception:\n"
                << code_string(EXCEPTION_STACK_OVERFLOW) << '\n';
    std::cerr << "Terminating." << std::endl;

    // can print a stack dump of the failed
    // thread to see what went wrong, etc...

    std::exit(EXIT_FAILURE);
}

void exception_translator(unsigned pCode, _EXCEPTION_POINTERS*)
{
    // minimize function calls if it's a stack overflow
    if (pCode == EXCEPTION_STACK_OVERFLOW)
    {
        // do some additional processing in another thread,
        // because the stack of this thread is gone
        boost::thread t(stack_fail_thread);
        t.join(); // will never exit
    }
    else if (!ignore_exception(pCode))               
    {
        // can add a stack dump to the exception message,
        // since these tend to be pretty severe, etc...
        BOOST_THROW_EXCEPTION(std::runtime_error(code_string(pCode)));
    }
}

void hook_signals()
{
    _set_se_translator(exception_translator);
}

我剥掉了几件事，但你明白了。您可以通过这种方式提取所有相同的信息。

VS2008使用SEH启用C ++异常

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