Re: Help wanted on some source codes

slebetman@xxxxxxxxx said:

> But I didn't think all globals are external
> linkage by default. I thought you need to use the 'extern' keyword for
> that.

No. When you do this:

extern int foo;

you are saying "dear compiler, I promise to you that there is an object
called foo, which is an int, but its storage is already reserved elsewhere
so you don't need to reserve any; just trust me on this". Each translation
unit needing to read or write foo (EXCEPT ONE) will need to have such a
line. Typically, such lines are put into a header.

In exactly one place in your program (at file scope), you must keep your
promise:

int foo;

The translation unit that has this line need not have an extern int foo; as
well (although it will do no harm if it does).

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at above domain (but drop the www, obviously)
.

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