Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!1.eu.feeder.erje.net!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Spurious diagnostic messages
Date: Sun, 17 May 2015 07:58:49 -0700
Organization: None to speak of
Lines: 17
Message-ID: <87k2w79ro6.fsf@kst-u.example.com>
References: <mha5pl$vtt$1@dont-email.me> <mj1n23$24o$1@dont-email.me> <55586ec4.5718781@news.xs4all.nl> <mja44d$n5p$1@dont-email.me> <mja62k$df6$2@news.xmission.com> <mja6uv$10b$1@dont-email.me>
Mime-Version: 1.0
Content-Type: text/plain
Injection-Info: mx02.eternal-september.org; posting-host="9be37d943435275679235b07c7947eef"; logging-data="12449"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18wzKTf86XoIRdeEjb0+iMS"
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)
Cancel-Lock: sha1:QLqNeE6Yytke13GyfF6c2+qFQvw= sha1:VtL09uw+qUr2kcI+8SJ3PL+xqfU=
Xref: csiph.com comp.lang.c:62164

Bartc <bc@freeuk.com> writes:
[...]
> if (!!isupper) ...
[...]

I don't know what this is in response to, but I presume you didn't
mean that literally.  The expression `!!isupper` simply yields 1,
since isupper is of function pointer type and is non-null.

You can certainly use the result of isupper() in an if statement, but
there's no need to apply `!!` to it.

-- 
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"