Catching floating exceptions

[usenet]

I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

Thanks,
Song

[Ian Collins]

us****@sta.sams ung.com wrote:

I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

You can't. At least not in standard C++, there might be platform
specific extensions, but hardware generated traps are not the same as
C++ language exceptions.

--
Ian Collins.

[Jim Langston]

<us****@sta.sam sung.comwrote in message
news:11******** **************@ p77g2000hsh.goo glegroups.com.. .

>I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

Is the problem that no exception is thrown? An integer divide by zero will
throw a system error, a floating point divide by error should return
infinity or negative infinity. Consider the following program I just threw
together. There is probably a better way, but I'm just not sure what it is.

#include <iostream>
#include <cfloat>

int main()
{

float Zero = 0.0f;
float Inf = 5.0f / Zero;
float NegInf = -5.0f / Zero;

float x = -5.0f;
float y = 0.0f;
float z = x/y;

std::cout << z << "\n";
if ( z == Inf || z == -Inf )
std::cout << "Division By Zero (infinity) " << "\n";

return 0;
}

[Rolf Magnus]

us****@sta.sams ung.com wrote:

I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

The first thing you should do is decide whether you are programming in C++
or in D.

[terminator]

On Jun 1, 5:41 am, [e-mail] ung.com wrote:

I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

Thanks,
Song

using C (not C++) libraries you can do this via 'signals' and you need
use 'setjmp' and 'longjmp' functions which are not commonly used since
the new exception handling mechanism(try-catch-throw) has been
introduced. I am not certain on details but you need read
documentations on 'signal' mechanism .

[James Kanze]

On Jun 1, 3:48 am, Ian Collins <[e-mail] mwrote:

[e-mail] ung.com wrote:

I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

You can't. At least not in standard C++, there might be platform
specific extensions, but hardware generated traps are not the same as
C++ language exceptions.

In general (on a machine with IEEE floating point), divide by 0
will not generate an exception. Nor a hardware trap, nor
anything else that will interrupt normal program flow. On most
systems, anything floating point error which will cause a
hardware trap will be mapped to SIGFPE, which you can trap, but
you can't throw an exception from a signal handler, so that may
not solve the problem either.

--
James Kanze (GABI Software) email:ja******* **@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

[Rolf Magnus]

terminator wrote:

On Jun 1, 5:41 am, [e-mail] ung.com wrote:

>I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

Thanks,
Song

using C (not C++) libraries you can do this via 'signals'

.... on some systems

and you need use 'setjmp' and 'longjmp' functions which are not commonly
used since the new exception handling mechanism(try-catch-throw) has been
introduced.

There are compilers that actually implement try/catch/throw by means of
setjmp and longjmp.

[terminator]

On Jun 1, 9:29 pm, Rolf Magnus <[e-mail]:

terminator wrote:

On Jun 1, 5:41 am, [e-mail] ung.com wrote:

I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

Thanks,
Song

using C (not C++) libraries you can do this via 'signals'

... on some systems

and you need use 'setjmp' and 'longjmp' functions which are not commonly
used since the new exception handling mechanism(try-catch-throw) has been
introduced.

There are compilers that actually implement try/catch/throw by means of
setjmp and longjmp.

but I do not think it is possible to change the way try/catch/throw
without switching to another compiler

[terminator]

On Jun 2, 2:32 pm, terminator <farid.mehr...@ gmail.comwrote:

>
but I do not think it is possible to change the way try/catch/throw
without switching to another compiler- Hide quoted text -

- Show quoted text -

Sorry.but I do not think it is possible to change the way try/catch/
throw behaves without switching to another compiler.

regards,
FM

[terminator]

On Jun 1, 5:45 pm, James Kanze <james.ka...@gm ail.comwrote:

On Jun 1, 3:48 am, Ian Collins <[e-mail] mwrote:

[e-mail] ung.com wrote:

I am unable to catch floating exceptions (e.g. divide by 0 or 0/0)
using the standard exceptions defined in stdexcept. What is the
recommended way to catch such exceptions?

You can't. At least not in standard C++, there might be platform
specific extensions, but hardware generated traps are not the same as
C++ language exceptions.

In general (on a machine with IEEE floating point), divide by 0
will not generate an exception. Nor a hardware trap, nor
anything else that will interrupt normal program flow. On most
systems, anything floating point error which will cause a
hardware trap will be mapped to SIGFPE, which you can trap, but
you can't throw an exception from a signal handler, so that may
not solve the problem either.

--
James Kanze (GABI Software) email:james.ka. [e-mail]
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

wont it be good to provide a standard for libraries so as to declare
functions that convert old style exceptions to new ones?
currently ,static variable constructors also may throw exceptions that
I am not sure could be catched.