Re: trapping SIGFPE

[Andreas Jaeger]

Peter Jay Salzman <address@hidden> writes:

> dear all,
>
> i can't seem to trap any kind of floating point exception:
>
>    #include <stdio.h>
>    #include <signal.h>
>    static void Exception(int signum);
>    
>    int main(void)
>    {
>       float bignum = 9E350;
>       float smallnum = 9E-350;
>    
>       signal(SIGFPE, Exception);
>    
>       printf("%p\n", sigreturn);
>       printf("%Lf\n", 2.0L / 0.0L);
>       printf("%Le\n", bignum / smallnum);
>       return 0;
>    }
>    
>    
>    void Exception(int signum)
>    {
>       printf("Caught SIGFPE: %d.\n", signum);
>       exit(0);
>    }
>
> SIGFPE isn't being caught, even though (i believe) i correctly installed
> a signal handler.
>
> what's going on here?   how would i modify this program to catch an
> overflow, underflow or divide by zero?

Use the functions from <fenv.h> to enable trapping.  By default we do
not trap for fp exceptions.

Andreas
-- 
 Andreas Jaeger
  SuSE Labs address@hidden
   private address@hidden
    http://www.suse.de/~aj