除以零会导致启用浮点异常的异常吗？ [英] Should divide by zero cause an exception with floating point exceptions enabled?

问题描述

我一直在VS2015中调试一个C ++应用程序，发现我的一些双变量在除以零后结束了NaN。虽然这是合理的，但我启用了浮点异常（/ fp：except），所以我希望
这可以引发异常。查看 

Edit2： 进一步阅读  这里  on
IEE 754告诉我，如果启用了浮点异常，我应该得到一个例外。但是对先前链接的问题的评论却表明  '
名称"浮点异常"是一个历史误称。浮点除零是明确定义的（根据附件F / IEEE754）并且不产生任何信号。 / em>

解决方案

看看
https://social.msdn.microsoft .com /论坛/ zh-CN / da4beb88-24c0-4e9b-97c4-7f42e34e5596 / why-am-i-not-getting-any-floating-point-exceptions？forum = vcgeneral

另外，如果你想使用C ++ try / catch（...）捕获结构化异常，你需要用/ EHa编译 - 参见

https://docs.microsoft.com / en-us / cpp / build / reference / eh-exception-handling-model？view = vs-2017  以及

https://docs.microsoft.com/en-us/cpp/cpp/exception-处理差异？view = vs-2017

I've been debugging a C++ application in VS2015 and found that a number of my double variables were ending up a NaN following a divide by zero. While this is reasonable, I have floating point exceptions enabled (/fp:except) so I would have expected this to raise an exception. Looking at the MS help page, it doesn't list what causes a floating point exception. According to this answer to a related question, divide by zero is a floating point exception. This is not the case, i.e. the following test program with /fp:except enabled

int main()
{
    try
    {
        double x = 1;
        double y = 0;
        double z = x / y;
        printf("%f\n", z);
        return 0;
    }
    catch (...)
    {
        printf("Exception!\n");
        return 0;
    }
}

displays "inf". Should this raise a floating point exception?

Edit: Checked the exceptions were enabled in the debugger and get the same result regardless 

Edit2: Further reading here on IEE 754 suggests to me that with floating point exceptions enabled I should be getting an exception. A comment to the previously linked question however states 'The name "floating point exception" is a historical misnomer. Floating point division by zero is well-defined (per Annex F/IEEE754) and does not produce any signal.'

解决方案

Have a look at https://social.msdn.microsoft.com/Forums/en-US/da4beb88-24c0-4e9b-97c4-7f42e34e5596/why-am-i-not-getting-any-floating-point-exceptions?forum=vcgeneral

Also, if you want to catch a structured exception using C++ try/catch(...) you need to compile with /EHa -- see https://docs.microsoft.com/en-us/cpp/build/reference/eh-exception-handling-model?view=vs-2017 and also https://docs.microsoft.com/en-us/cpp/cpp/exception-handling-differences?view=vs-2017

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