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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Could you explain what meanings are in this time help contents?
Date: Sun, 29 Jan 2017 13:26:07 -0800
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fl <rxjwg98@gmail.com> writes:
> I want to learn ctime usage. Accidentally see the following link:
>
> http://ps-2.kev009.com/wisclibrary/aix51/usr/share/man/info/en_US/a_doc_lib/libs/basetrf1/ctime.htm#SPTA0909BAC
>
> It is noticed that the first line in each pair has no ';' at the end.
> It is puzzling to me for their meanings.
> There are three same lines beginning with 'const'.
>
> Could you explain to me what each pair is for?
[...]
> #include <time.h>
>
>
> char *ctime ( Clock)
> const time_t *Clock;

This is part of an old-style (pre-ANSI) function declaration.

This form is still legal, but there is no good reason to use it
(unless you're stuck with a *very* old compiler, but that's not
likely).  The modern and more correct declaration, copy-and-pasted
from the C Standard, is:

    char *ctime(const time_t *timer);

The name of the parameter is not particularly relevant, but "timer" is
what's used in the standard.  The name "Clock" is poorly chosen, since
there's a clock() function with a quite different meaning.

That web page is part of a technical reference for AIX, a flavor of UNIX
from IBM.  It seems to be fairly old.  Unless you're using an old
version of AIX for some reason, I strongly suggest you find a better
reference.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"