Hi Marlin,
> What is the life span of a #define or #include. Is it to the end of the C
> file that defined or included it?
The preprocessor converts your input file with all #includes and #defines
into one big chunk of C-Code which is then read by the actual compiler. So
a #define is not only in effect in your source-file but in all files
that you include (and in turn are included by them...) afterwards.
> Is the #define or #include stuff flushed before the next C files is
> analyzed?
Every C-file is (at least with gcc, other compilers might have some
magic pre-compiled headers/libraries/...) compiled independent of
every other file.
> Somewhere I read that it is bad programming style to include
> include files from an include file. Is this TRUE?
No, it's perfectly OK to include files in every other file.
It may be a matter of taste and complexity of maintainance, though.
I would advise to read some good books on this topic first! ;-)
> Does someone know of a good source of info so I can get a grip on how the
> preprocessor works? I want to understand how to intellegently use the
> #define #ifdef #ifndef stuff, instead of tumbling around with it.
The gcc-documentation might be a good start, and every good C-Book should
explain the preprocessor!
Chris
--
The problem with bad plans is, for each one created, there's an
idiot somewhere willing to carry it out -- Kirk Mitchell