Path: utzoo!attcan!uunet!decwrl!apple!vsi1!octopus!pete
From: pete@Octopus.COM (Pete Holzmann)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Turbo C matherr() function
Summary: Deal with SIG_FPE too!
Message-ID: <1990Aug3.131340.16334@Octopus.COM>
Date: 3 Aug 90 13:13:40 GMT
References: <1990Aug1.125327.26101@watserv1.waterloo.edu>
Reply-To: pete@octopus.COM (Pete Holzmann)
Distribution: comp
Organization: Octopus Enterprises, Cupertino CA
Lines: 28

broehl@watserv1.waterloo.edu (Bernie Roehl) writes:
>The problem is simple... maybe the solution will be, too.
>I'm trying to define my own matherr() function, as described on page 242 of
>the Reference Guide.
>
>I then write a short program that just divides by zero, link it with the above,
>and run it.  Instead of "Hello, world!\n", I get the standard Turboc C
>"Floating point error: Divide by 0".
>
>Any ideas/suggestions/etc will be much appreciated.  Thanks in advance...

Unfortunately, the solution is not as simple as you would like.

matherr() only deals with the errors that it is documented to deal
with. Basically, it is only called when an error is generated within
the trig/exponential functions.

To handle divide by zero and a host of other problems, you must set
up a signal handler for SIG_FPE (see signal()). This also requires 
careful use of setjmp() and longjmp(). Which can be truly a pain in
the neck!

Pete
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