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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Is 'extern' necessary?
Date: Mon, 13 Feb 2017 11:06:24 -0800
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GOTHIER Nathan <nathan.gothier@gmail.com> writes:
[...]
> Prototypes should always be declared as "extern" since it points to a previous
> definition.

In what sense is the definition necessarily "previous", and why would
that argue in favor of using "extern"?

At file scope, this:
    extern void foo(void);
and this:
    void foo(void);
mean exactly the same thing.  I don't object to adding the "extern"
keyword if you think it makes it clearer, but it's not required.

-- 
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"