fmt: handle precision 0 format stings in standard way

fmt: handle precision 0 format stings in standard way

The C-stdlib heritage of printf/fprintf/sprintf has two odd
aspects for precisions of zero with integers. First, the zero
can be specified in any of these ways, "%4.0d", "%.0d" and
"%.d" which was not previously supported here. Secondly, the
seemingly universal interpretation of precision for integers
is that precision==0 and value==0 means print nothing at all.
The code here now handles this for integers just as the code
in big/int.c does the same for the Int type. New tests are
added to fmt_test.go to verify these changes.

[r, 2011-07-21 06:45:15]

http://codereview.appspot.com/4717045/diff/2001/src/pkg/fmt/fmt_test.go
File src/pkg/fmt/fmt_test.go (right):

http://codereview.appspot.com/4717045/diff/2001/src/pkg/fmt/fmt_test.go#newco...
src/pkg/fmt/fmt_test.go:185: {"%.d", 0, ""},
shouldn't there be non-zero test cases, the reason for the change?

[r, 2011-07-21 06:46:00]

apologies, never mind. i'm a CL behind.
LGTM

[r, 2011-07-21 06:47:06]

*** Submitted as http://code.google.com/p/go/source/detail?r=8f4c6113ed2d ***

fmt: handle precision 0 format stings in standard way

The C-stdlib heritage of printf/fprintf/sprintf has two odd
aspects for precisions of zero with integers. First, the zero
can be specified in any of these ways, "%4.0d", "%.0d" and
"%.d" which was not previously supported here. Secondly, the
seemingly universal interpretation of precision for integers
is that precision==0 and value==0 means print nothing at all.
The code here now handles this for integers just as the code
in big/int.c does the same for the Int type. New tests are
added to fmt_test.go to verify these changes.

R=r, r
CC=golang-dev
http://codereview.appspot.com/4717045

Committer: Rob Pike <r@golang.org>

[mtj1, 2011-07-21 06:51:01]

Great, thanks. One less dangling change in my tree!

Michael T. Jones | Chief Technology Advocate  | mtj@google.com |  +1
650-335-5765



On Wed, Jul 20, 2011 at 11:47 PM, <r@golang.org> wrote:

> *** Submitted as
>
http://code.google.com/p/go/**source/detail?r=8f4c6113ed2d<http://code.google...
>
> fmt: handle precision 0 format stings in standard way
>
> The C-stdlib heritage of printf/fprintf/sprintf has two odd
> aspects for precisions of zero with integers. First, the zero
> can be specified in any of these ways, "%4.0d", "%.0d" and
> "%.d" which was not previously supported here. Secondly, the
> seemingly universal interpretation of precision for integers
> is that precision==0 and value==0 means print nothing at all.
> The code here now handles this for integers just as the code
> in big/int.c does the same for the Int type. New tests are
> added to fmt_test.go to verify these changes.
>
> R=r, r
> CC=golang-dev
>
> http://codereview.appspot.com/**4717045<http://codereview.appspot.com/4717045>
>
> Committer: Rob Pike <r@golang.org>
>
>
>
>
http://codereview.appspot.com/**4717045/<http://codereview.appspot.com/4717045/>
>