Re^2: C macro pre processing

As far as I understand gcc -E , it expands all macros to their definition, while the OP seems to want to only remove the parts that vanish due to their guarding #define being false or not defined.

That doesn't fit the problem description, but it might well be the solution the OP wants.

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Re^3: C macro pre processing by BrowserUk (Patriarch) on Jun 24, 2012 at 07:56 UTC
Ah! Yes, I can see the utility of such a tool. It would be very useful when exploring complex code. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. The start of some sanity?	[reply]
Re^4: C macro pre processing by afoken (Chancellor) on Jun 24, 2012 at 07:59 UTC
unifdef looks promising. Update: The current unifdef-2.6 does not process the `#define`s included from `types.h`, so for the trivial command `unifdef types.c -o output.txt`, the output is unchanged. Using the brain to parse `types.h`, one can define `ALPHA`, `BETA`, and `GAMMA` via the command line: `unifdef -DALPHA=1 -DBETA -DGAMMA=0 types.c -o output.txt`, but unfortunately, this removes all preprocessor commands, not only the `GAMMA` commands. So, to get rid of only the `GAMMA` commands, one has to define only `GAMMA` on the command line: `unifdef -DGAMMA=0 types.c -o output.txt`. This gives the expected result. Update 2: `unifdef` seems to completely ignore `#include` and `#define`. So, `types.h` is not read at all, and even if it would be read, the `#define`s have no effect. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]