Re: printf %b

[Alejandro Colomar <colomar.6.4.3@gmail.com>]

On 4/26/20 2:54 AM, Jonathan Nieder wrote:
> Hi!
> 
> Alejandro Colomar wrote:
> 
>> In my personal library, about a year ago, I wrote a function to register the
>> ``b`` and ``B`` conversion specifiers using ``register_printf_specifier()``.
>>
>> They work the closest possible to ``o``, ``u``, ``x`` & ``X``:
> 
> You left out the key detail up here, that it writes a number in
> binary. :)

Yup, I forgot the main point :)

> 
> The printf command line utility uses %b for something else: it prints
> its argument as an expanded string, with backslashes interpolated.
> For example, "foo\\tbar" becomes "foo	bar".  I think this is enough
> reason not to use %b for something else in libc out of the box.  Of

Hmmm.  Good point.  Maybe, given that binary doesn't have letters such 
as hex does, we don't need both ``%b`` and ``%B``.  We could have just 
``%B`` (if it isn't already taken by some other thing) and use it for 
binary.

> course, particular programs registering a printf specifier are a
> separate story.
> 
> That said, I don't want to discourage a potential glibc contributor.
> For what it's worth, glibc's printf code is pretty messy and I would
> be very happy to review a proposal for cleaning it up.

I can try.  I do agree that it is messy; maybe too much for me to 
understand it.

> 
> Thanks and hope that helps,
> Jonathan


Thank you very much.

		Alex.