Date: Sun, 02 Nov 2014 11:20:03 +0800 From: Julian Elischer <julian@freebsd.org> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: Freebsd hackers list <freebsd-hackers@freebsd.org> Subject: Re: how to kernel printf a int64_t? Message-ID: <5455A2E3.40808@freebsd.org> In-Reply-To: <604180572.3888597.1414894484998.JavaMail.root@uoguelph.ca> References: <604180572.3888597.1414894484998.JavaMail.root@uoguelph.ca>
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On 11/2/14, 10:14 AM, Rick Macklem wrote:
> Julian Elischer wrote:
>> On 10/31/14, 1:09 PM, Tim Kientzle wrote:
>>
>>
>> On Oct 30, 2014, at 2:01 PM, Rick Macklem <rmacklem@uoguelph.ca>
>> wrote:
>>
>> Hi,
>>
>> I feel kinda dumb asking this, but...
>> int64_t i;
>>
>> printf("%qd\n", (u_quad_t)i);
>>
>> works but looks dorky, to put it technically;-).
>> Is there a better way to printf() a int64_t in the kernel? I often
>> use the following to print large integers:
>>
>> printf(“%jd\n”, (intmax_t)i); the "cannonical' way is to use
>> PRIu64 and friends, but some people seem to have a problem with
>> doing that.
>>
> Ok, so now I need to ask another dumb question.
> How do you do this in the kernel?
> (I can see them defines in <machine/_inttypes.h>, but including that
> doesn't help, which isn't surprising since PRIu64 is in a string
> and won't be recognized as a macro.)
you use it with string concatenation.
like:
printf (" this is a 64 it unsigned value: %" PRIu64 " and I just
printed it\n", thingy64);
After substitution the compiler sees
" this is a 64 it unsigned value: %" "llu" " and I just printed it\n"
which simplifies to:
" this is a 64 it unsigned value: %llu and I just printed it\n"
due to concatenation. (note I didn't actually look what PRIu64
evaluates to)
>
> Oh, and is intmax_t going to be int64_t on all arches?
>
> Thanks, rick
>
>>
>> Tim
>>
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>
>
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