* reading sNaN
@ 2023-10-10 13:41 Paul Zimmermann
2023-10-10 14:23 ` Vincent Lefevre
0 siblings, 1 reply; 2+ messages in thread
From: Paul Zimmermann @ 2023-10-10 13:41 UTC (permalink / raw)
To: libc-alpha
Hi,
it seems currently the GNU libc can read the following character sentences
through scanf ("%la", &x) : [+-]nan, [+-]inf, where nan means a quiet NaN.
Is is planned to also read signaling NaNs as [+-]snan?
Paul
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: reading sNaN
2023-10-10 13:41 reading sNaN Paul Zimmermann
@ 2023-10-10 14:23 ` Vincent Lefevre
0 siblings, 0 replies; 2+ messages in thread
From: Vincent Lefevre @ 2023-10-10 14:23 UTC (permalink / raw)
To: libc-alpha
On 2023-10-10 15:41:05 +0200, Paul Zimmermann wrote:
> it seems currently the GNU libc can read the following character sentences
> through scanf ("%la", &x) : [+-]nan, [+-]inf, where nan means a quiet NaN.
But it is buggy as it doesn't support the form with parentheses:
https://sourceware.org/bugzilla/show_bug.cgi?id=30647
> Is is planned to also read signaling NaNs as [+-]snan?
Has this been put in the C23 draft?
FYI, here's what the IEEE 754-2019 says:
Conversion of an external character sequence “snan” (regardless
of case) with an optional preceding sign, to a supported format
should either produce a signaling NaN or else produce a quiet NaN
and signal the invalid operation exception.
--
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
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