Re: Handling Floating Point Exception in VC++ 6.0

From:

"Ben Voigt [C++ MVP]" <rbv@nospam.nospam>

Newsgroups:

microsoft.public.vc.language

Date:

Fri, 26 Dec 2008 17:59:13 -0600

Message-ID:

<1F7E68CD-5B2C-4835-A075-16551CA5DB5C@microsoft.com>

"SONET" <SONET@discussions.microsoft.com> wrote in message
news:309A110A-6060-49FD-B162-B17CB7C27398@microsoft.com...

I've been trying to handle floating point exceptions but I am having some
problems.

Basically I am able to catch the exception with the catch(...), I wrote a
class that should be thrown but it is not working.

Have a look at __try/__except and GetExceptionCode.

http://msdn.microsoft.com/en-us/library/ms679356(VS.85).aspx

I basically coded the following class

FloatException::FloatException( int nSubCode )
{
   subCode = nSubCode;
   _fpreset();
}

void FloatException::FloatExceptionHandler( int sig, int nSubCode )
{
   throw( new FloatException( nSubCode ) );
}

void FloatException::SetFloatExceptionHandler()
{
   // Get the current floating point control word.
   //unsigned int uWord = _controlfp( 0, 0 );

   unsigned int uWord = 0;

   // Set the exceptions we want
   uWord |= _EM_UNDERFLOW;
   uWord |= _EM_OVERFLOW;
   uWord |= _EM_ZERODIVIDE;
   uWord |= _EM_INVALID;

   _controlfp(uWord, _MCW_EM);

   uWord = _controlfp( 0, 0 );

   // Set the exception handler.
   signal( SIGFPE, (void (__cdecl*)(int))FloatExceptionHandler );
}

in the main code I do this

FloatException::SetFloatExceptionHandler();
try
{
double temp = exp(99999999);
}
catch(FloatException& e)
{
}
catch(...)
{

}

the problem is that it never hits the FloatException catch, and it never
executes the FloatExceptionHandler. it does get caught in the catch(...)
which didn't do before I wrote the code.

Is there something I am missing? Is there a better way to do floating
point
exception.

I am running Windows XP on a Xeon. Does the processor matter?