From: Andy Shevchenko <email@example.com> To: Joe Perches <firstname.lastname@example.org> Cc: Jonathan Corbet <email@example.com>, Linux Documentation List <firstname.lastname@example.org>, linux-kernel <email@example.com>, Louis Taylor <firstname.lastname@example.org> Subject: Re: [PATCH] docs: printk-formats: Stop encouraging use of unnecessary %h[xudi] and %hh[xudi] Date: Sat, 7 Sep 2019 23:23:53 +0300 [thread overview] Message-ID: <CAHp75Vc=hSTWzSDToijXJGWxiHA1JOA2e8R0YYmETQ+tTfVhYw@mail.gmail.com> (raw) In-Reply-To: <email@example.com> On Sat, Sep 7, 2019 at 9:15 PM Joe Perches <firstname.lastname@example.org> wrote: > > Standard integer promotion is already done and %hx and %hhx is useless > so do not encourage the use of %hh[xudi] or %h[xudi]. > > As Linus said in: > Link: https://lore.kernel.org/lkml/CAHk-=wgoxnmsj8GEVFJSvTwdnWm8wVJthefNk2n6+4TC=20e0Q@mail.gmail.com/ > > It's a pointless warning, making for more complex code, and > making people remember esoteric printf format details that have no > reason for existing. > > The "h" and "hh" things should never be used. The only reason for them > being used if if you have an "int", but you want to print it out as a > "char" (and honestly, that is a really bad reason, you'd be better off > just using a proper cast to make the code more obvious). > > So if what you have a "char" (or unsigned char) you should always just > print it out as an "int", knowing that the compiler already did the > proper type conversion. > - char %hhd or %hhx > - short int %hd or %hx > + char %d or %x > + short int %d or %x > + s8 %d or %x > + s16 %d or %x This is incorrect. Integral promotions promotes also sign, which will produce too many f:s. -- With Best Regards, Andy Shevchenko
next prev parent reply other threads:[~2019-09-07 20:24 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-09-06 21:11 Joe Perches 2019-09-06 21:37 ` Louis Taylor 2019-09-07 20:23 ` Andy Shevchenko [this message] 2019-09-09 9:36 ` Jani Nikula 2019-09-14 7:58 ` Jonathan Corbet
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