Re: What is the class of a loating point exception ?
On 2007-03-18 16:44, EvilOldGit@googlemail.com wrote:
On 18 Mar, 14:24, Erik Wikstr?m <Erik-wikst...@telia.com> wrote:
On 2007-03-18 14:26, EvilOld...@googlemail.com wrote:
In Stroustrup he talks of a MathErr class that you can use to catch
floating point exceptions.
It doesn't exist, at least not in Visual C++
I can catch FP exceptions using catch(...) but am stumped in finding
out what the class I'm catching is.
I would like to know how to catch them in a more elegant way than
catch(...) and then poling around in registers to guess the problem.
In general floating point errors do not throw exceptions in C++, for example
double i = 0;
double j = 1/i;
will not throw an exception (it will however terminate your app). If you
want to handle floating point errors in C++ you have to check for them
yourself and throw an appropriate exception. One way tho do this is to
encapsulate float/double in a class with the same interface as dloat/
double but which performs those checks.
--
Erik Wikstr?m
I'm using VC++, and if you set the flags, it will throw an exception
on div/0 et al.
I've always done what Erik suggests, using test & throw, but have long
felt I could do a lot better.
I *nearly* have.
VC++ will throw a proper C++ style exception (not a Win32 SEH one)
But I ca'nt catch it.
If I could determine the type of exception I could then drill down
better.
Leaving the land of standardized C++ behind... It does not say in the
documentation of VC? An alternative, while not exactly what you want,
but couldn't you just
try {
/* FP OP */
}
catch (...) {
throw MyFPException;
}
This works if you can enclose the possible throwing FP operations with
try but at the same time be sure that no other exception can be thrown
in that section.
--
Erik Wikstr?m
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