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* [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64)
@ 2010-04-07 8:40 zimmerma+gcc at loria dot fr
2010-04-07 9:11 ` [Bug libc/11475] " vincent+libc at vinc17 dot org
` (8 more replies)
0 siblings, 9 replies; 11+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2010-04-07 8:40 UTC (permalink / raw)
To: glibc-bugs
as far as I know, the current glibc does not print/read decimal formats
(_Decimal64 for example). Is there any plan to support this?
Example code:
#include <stdio.h>
int
main()
{
double d = 0.1;
_Decimal64 e = 0.1;
printf ("%.20f\n", d);
printf ("%.20f\n", e);
}
gives:
tarte% gcc bug.c
tarte% ./a.out
0.10000000000000000555
0.00000000000000000000
We expect 0.10000000000000000000 for the second output.
--
Summary: support for printing/reading decimal numbers
(_Decimal64)
Product: glibc
Version: unspecified
Status: NEW
Severity: enhancement
Priority: P2
Component: libc
AssignedTo: drepper at redhat dot com
ReportedBy: zimmerma+gcc at loria dot fr
CC: glibc-bugs at sources dot redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=11475
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
@ 2010-04-07 9:11 ` vincent+libc at vinc17 dot org
2010-04-07 9:12 ` vincent+libc at vinc17 dot org
` (7 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: vincent+libc at vinc17 dot org @ 2010-04-07 9:11 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From vincent+libc at vinc17 dot org 2010-04-07 09:11 -------
The code is invalid. %f takes an argument of type double, not a _Decimal64. You
need the D modifier (see WG14/N1312, 9.5 Formatted input/output specifiers), e.g.
%Df.
--
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
2010-04-07 9:11 ` [Bug libc/11475] " vincent+libc at vinc17 dot org
@ 2010-04-07 9:12 ` vincent+libc at vinc17 dot org
2010-04-07 9:16 ` zimmerma+gcc at loria dot fr
` (6 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: vincent+libc at vinc17 dot org @ 2010-04-07 9:12 UTC (permalink / raw)
To: glibc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |vincent+libc at vinc17 dot
| |org
http://sourceware.org/bugzilla/show_bug.cgi?id=11475
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
2010-04-07 9:11 ` [Bug libc/11475] " vincent+libc at vinc17 dot org
2010-04-07 9:12 ` vincent+libc at vinc17 dot org
@ 2010-04-07 9:16 ` zimmerma+gcc at loria dot fr
2010-04-07 9:17 ` vincent+libc at vinc17 dot org
` (5 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2010-04-07 9:16 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From zimmerma+gcc at loria dot fr 2010-04-07 09:15 -------
Vincent, you are right. With printf ("%.20Df\n", e) I get:
tarte% gcc bug.c
tarte% ./a.out
0.10000000000000000555
%.20Df
which is not very useful...
Paul
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
` (2 preceding siblings ...)
2010-04-07 9:16 ` zimmerma+gcc at loria dot fr
@ 2010-04-07 9:17 ` vincent+libc at vinc17 dot org
2010-04-07 9:25 ` vincent+libc at vinc17 dot org
` (4 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: vincent+libc at vinc17 dot org @ 2010-04-07 9:17 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From vincent+libc at vinc17 dot org 2010-04-07 09:17 -------
With a corrected code:
#include <stdio.h>
int main (void)
{
double d = 0.1;
_Decimal64 e = 0.1;
printf ("%.20f\n", d);
printf ("%Da\n", e);
printf ("%De\n", e);
printf ("%Df\n", e);
printf ("%Dg\n", e);
return 0;
}
currently gives:
0.10000000000000000555
%Da
%De
%Df
%Dg
--
http://sourceware.org/bugzilla/show_bug.cgi?id=11475
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
` (3 preceding siblings ...)
2010-04-07 9:17 ` vincent+libc at vinc17 dot org
@ 2010-04-07 9:25 ` vincent+libc at vinc17 dot org
2010-04-07 9:38 ` schwab at linux-m68k dot org
` (3 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: vincent+libc at vinc17 dot org @ 2010-04-07 9:25 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From vincent+libc at vinc17 dot org 2010-04-07 09:25 -------
Also, this doesn't matter now, but if accuracy needs to be taken into account
(once this is implemented), one should use
_Decimal64 e = 0.1dd;
for the tests, instead of:
_Decimal64 e = 0.1;
--
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
` (4 preceding siblings ...)
2010-04-07 9:25 ` vincent+libc at vinc17 dot org
@ 2010-04-07 9:38 ` schwab at linux-m68k dot org
2010-04-07 13:30 ` drepper at redhat dot com
` (2 subsequent siblings)
8 siblings, 0 replies; 11+ messages in thread
From: schwab at linux-m68k dot org @ 2010-04-07 9:38 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From schwab at linux-m68k dot org 2010-04-07 09:37 -------
*** Bug 11476 has been marked as a duplicate of this bug. ***
--
http://sourceware.org/bugzilla/show_bug.cgi?id=11475
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
` (5 preceding siblings ...)
2010-04-07 9:38 ` schwab at linux-m68k dot org
@ 2010-04-07 13:30 ` drepper at redhat dot com
2010-04-07 15:30 ` vincent+libc at vinc17 dot org
2010-04-28 8:15 ` zimmerma+gcc at loria dot fr
8 siblings, 0 replies; 11+ messages in thread
From: drepper at redhat dot com @ 2010-04-07 13:30 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From drepper at redhat dot com 2010-04-07 13:30 -------
This is what the printf hooks are for. I'm not going to add any such
non-standard conversion. It far too dangerous a compability risk going forward.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |WONTFIX
http://sourceware.org/bugzilla/show_bug.cgi?id=11475
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
` (6 preceding siblings ...)
2010-04-07 13:30 ` drepper at redhat dot com
@ 2010-04-07 15:30 ` vincent+libc at vinc17 dot org
2010-04-28 8:15 ` zimmerma+gcc at loria dot fr
8 siblings, 0 replies; 11+ messages in thread
From: vincent+libc at vinc17 dot org @ 2010-04-07 15:30 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From vincent+libc at vinc17 dot org 2010-04-07 15:30 -------
The conversion is currently non-standard, but it may become standard in the
future. At that time, the status of this bug will have to be revised.
--
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
` (7 preceding siblings ...)
2010-04-07 15:30 ` vincent+libc at vinc17 dot org
@ 2010-04-28 8:15 ` zimmerma+gcc at loria dot fr
8 siblings, 0 replies; 11+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2010-04-28 8:15 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From zimmerma+gcc at loria dot fr 2010-04-28 08:15 -------
(In reply to comment #6)
> This is what the printf hooks are for. I'm not going to add any such
> non-standard conversion. It far too dangerous a compability risk going forward.
Dear Ulrich, please can you explain why this is "non-standard". With respect to
which standard? Is _Decimal64 standard?
Also, if someone provides changes to scanf/printf based on functions already
existing in libbid or libdecnumber (currently used internally by gcc) for
conversions between strings and decimal formats, would them be included in glibc?
--
http://sourceware.org/bugzilla/show_bug.cgi?id=11475
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* [Bug libc/11475] support for printing/reading decimal numbers (_Decimal64)
[not found] <bug-11475-131@http.sourceware.org/bugzilla/>
@ 2014-06-30 18:18 ` fweimer at redhat dot com
0 siblings, 0 replies; 11+ messages in thread
From: fweimer at redhat dot com @ 2014-06-30 18:18 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=11475
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
--- Comment #9 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
Subject: Re: support for printing/reading decimal numbers
(_Decimal64)
On Wed, 28 Apr 2010, zimmerma+gcc at loria dot fr wrote:
> ------- Additional Comments From zimmerma+gcc at loria dot fr 2010-04-28 08:15 -------
> (In reply to comment #6)
> > This is what the printf hooks are for. I'm not going to add any such
> > non-standard conversion. It far too dangerous a compability risk going forward.
>
> Dear Ulrich, please can you explain why this is "non-standard". With respect to
> which standard? Is _Decimal64 standard?
A Technical Report Type 2 (such as TR 24732) is not a standard or an
amendment to a standard.
> Also, if someone provides changes to scanf/printf based on functions already
> existing in libbid or libdecnumber (currently used internally by gcc) for
> conversions between strings and decimal formats, would them be included in glibc?
The functionality is in the libfdp add-on. This is an example of what the
add-on mechanism is for; it doesn't need to be in the core libc. (I
imagine the libdfp people will propose a scanf hook facility at some point
to allow that part to be fully implemented in an add-on. One remaining
DFP requirement relates to the predefined macro __STDC_DEC_FP__ but
unfortunately my proposal for a change which would also allow that to be
handled entirely within the add-on has stalled; see bug 10110.)
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2010-04-07 8:40 [Bug libc/11475] New: support for printing/reading decimal numbers (_Decimal64) zimmerma+gcc at loria dot fr
2010-04-07 9:11 ` [Bug libc/11475] " vincent+libc at vinc17 dot org
2010-04-07 9:12 ` vincent+libc at vinc17 dot org
2010-04-07 9:16 ` zimmerma+gcc at loria dot fr
2010-04-07 9:17 ` vincent+libc at vinc17 dot org
2010-04-07 9:25 ` vincent+libc at vinc17 dot org
2010-04-07 9:38 ` schwab at linux-m68k dot org
2010-04-07 13:30 ` drepper at redhat dot com
2010-04-07 15:30 ` vincent+libc at vinc17 dot org
2010-04-28 8:15 ` zimmerma+gcc at loria dot fr
[not found] <bug-11475-131@http.sourceware.org/bugzilla/>
2014-06-30 18:18 ` fweimer at redhat dot com
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