Re: Preprocessor, nested files etc.

From: Karl Heinz Buchegger (kbuchegg_at_gascad.at)
Date: 08/13/04 

Date: Fri, 13 Aug 2004 10:07:43 +0200

Florian wrote:
>
> then those macro definitions don't seem to stick. When the next cpp files is
> being processed, the header file is being included again - even though the
> macro was previously defined
>
> Is this normal, and where am I getting confused?

Each source code file (each *.cpp) is compiled independently of all others.
That's the way things work in C++.
And of course it makes sense. Your project consists of 10 files. The project
I am involved in, consists of more then 400 files. Consider I make a change
in one of them and the compiler is going to recompile everything (sometimes
we have to do this, it takes around 2 hours for a complete recompile).

When the compiler compiles a *.cpp file, it starts in a fresh state. Nothing
it has learned by compiling a previous source code file remains. Which is
a good thing, because it means it can compile a collection of *.cpp files
in any order it likes. If you make a change in one of them, only this file
needs to be recompiled and the linker will form a new executable from the
results of all the copilation steps (they are called 'object files' or 'machine
code files') 

-- 
Karl Heinz Buchegger
kbuchegg@gascad.at

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