Re: `nstrftime ()' prototype

[Jim Meyering]

address@hidden (Ludovic Courtès) wrote:
> Hi again,
>
> Jim Meyering <address@hidden> writes:
>
>> +/* Just like strftime, but with two more arguments:
>> +   POSIX requires that strftime use the local timezone information.
>> +   When __UTC is nonzero and tm->tm_zone is NULL or the empty string,
>> +   use UTC instead.  Use __NS as the number of nanoseconds in the
>> +   %N directive.  */
>> +size_t nstrftime (char *, size_t, char const *, struct tm const *,
>> +              int __utc, int __ns);
>
> Actually, I don't see `%N' documented in the glibc 2.7 manual.  Is it
> something newer?

%N is a GNU invention specific to nstrftime.  It is the reason for
the __ns argument: struct tm has no nanosecond information.

> The effect of `brokentime->tm_zone' isn't specified either.

Its existence is mentioned briefly in the mktime man page -- it's a
BSD-ism, so you can probably find more info in BSD-specific documentation.

> IIUC, glibc's `strftime ()' is equivalent to UTC == 0 and NS == 0,
> right?

Right.  It's also equivalent for any other value of NS.