Hi,

what is the specified behaviour for standard c math functions like
pow() regarding error situations? Are they supposed to throw expections?
I don't have the standard document available and the Josuttis book
doesn't clearly tell me.

Thanks

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520014not351861-0001@t-online.de (Johannes Reinelt) wrote in message news:<b6h6oh$s7c$04$1@news.t-online.com>...
> Hi,
>
> what is the specified behaviour for standard c math functions like
> pow() regarding error situations? Are they supposed to throw expections?
> I don't have the standard document available and the Josuttis book
> doesn't clearly tell me.
>
> Thanks
>
> ---

Since C doesn't have exceptions it would be most surprising if any of
those standard C math functions did throw an exception.  :-)
Seriously, the error behavior of those functions is described in the C
standard.  In most cases that involves setting errno or returning a
special value.

If you do not have a copy of the relevant standards you may download
them from www.ansi.org for a mere US$18 each for a .pdf version that
can be viewed using AcrobatReader from www.adobe.com.  That will
provide you with the definitive answers to your question.

Randy.

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Johannes Reinelt wrote:
> Hi,
>
> what is the specified behaviour for standard c math functions like
> pow() regarding error situations? Are they supposed to throw expections?
> I don't have the standard document available and the Josuttis book
> doesn't clearly tell me.
>
> Thanks

17.4.4.8/2 says "None of the functions from the Standard C library
shall report an error by throwing an exception, unless it calls a
program-supplied function that throws an exception."

(Probably the wording ought to read "No function from the Standard
C library shall report an error by throwing an exception, unless
that function calls a program-supplied function that throws an
exception."  I think the meaning is clear enough though that this
doesn't call for a DR.)

It also refers to footnote 176, which says that we can consider
the C library functions as having a throw() exception specification.

-- James.

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