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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: A question on variable scope, coming from a relative beginner
Date: Thu, 12 Nov 2015 17:11:55 -0800
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Jon Rossen <jonr17@comcast.net> writes:
> Hi all, I'm fairly new to programming and have a question on the C 
> language with regards to variable scope, compilers and the 'extern' 
> keyword.  I'm using a couple of books that seem to have info that is not 
> in keeping with my results.  Here's a simple little trivial code example 
> that illustrates the question:
>
> #include <stdio.h>
>
> int x = 999;
> void print_value(void);
>
> int main(void)
> {
> 	extern int x;     // This entire statement is not necessary to
>                            // get the proper results, why??
>
> 	printf("%d\n", x);
> 	print_value();
>
> 	return 0;
> }
>
> void print_value(void)
> {
> 	extern int x;    // This obviously is
> 	printf("%d\n", x);
> }
>
> Result: 999
>          999

The "extern int x;" declaration (not statement) is not necessary either
in main or in print_value.  The file-scope definition of x is visible in
both functions.

-- 
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"