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To: cygwin <cygwin AT cygwin DOT com>
From: Ken Brown <kbrown AT cornell DOT edu>
Subject: Floating point exception in strtod()
Message-ID: <dd5e98ea-8f39-1c4b-116c-37968cb3a52d@cornell.edu>
Date: Sat, 7 Apr 2018 13:40:05 -0400
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$ cat strtod_test.c
#include <stdio.h>
#include <stdlib.h>
#include <fenv.h>

int
main ()
{
   /* The following number comes from /usr/share/asymptote/ode.asy.  */
   const char *str = "121645100408832000.0";
   char *ptr;

   feenableexcept (FE_INVALID);
   strtod (str, &ptr);

   /* If there was an exception, the following will not get executed.  */
   printf ("No exception.\n");
}

$ gcc strtod_test.c

$ ./a
Floating point exception (core dumped)

[The above was on x86.  On x86_64 there's simply no output.]

I have no idea what's special about the number 121645100408832000.0, but 
the problem goes away if, for example, I replace the leading 1 by 2.

Ken

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