Re: Help wanted on some source codes

Richard Heathfield wrote:
> 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).
>

Ah yes, quite right. Extern merely means "it's somewhere else" not
"please export this". Thank you for reminding me.

.

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