sscanf problem

Dave Korn
Mon Apr 4 18:07:00 GMT 2005

----Original Message----
>From: Dave Korn
>Sent: 04 April 2005 18:51

> ----Original Message----
>> From: Michael Hines
>> Sent: 04 April 2005 19:43
>> The following program prints
>> i=1 x=0
>> instead of
>> i=0 x=10
>> when using the latest version of cygwin1.dll.
>> #include <stdio.h>
>> int main() {
>>          int i;
>>          double x;
>>          x = 10;
>>          i = sscanf("n", "%lf", &x);
>>          printf("i=%d x=%g\n", i, x);
>>          return 0;
>> }
>> -Michael Hines
>   Heh, the interminable newlib-sscanf-bug strikes again!  It's mis-parsing
> the n as being the first letter of 'nan', which is a valid input to %f. 
> CV sent a patch upstream to the newlib maintainers last week but I guess
> it hasn't made it into the source yet.

  No, hang on, on checking the newlib-l archive that seems to have been
something to do with a zero exponent.  This is a separate bug: it accepts
the first one or two characters of 'nan' and says "ok, everything's still
good", and then because it's reached the end of the string it treats that as
a successful parse; it forgets to verify that it doesn't have an outstanding
half-formed NaN.  I'll post a (provisional) patch shortly.

Can't think of a witty .sigline today....

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