Preprocess, but do not expand macros?

Preprocess, but do not expand macros?

[Larry Riedel]

Is there a simple way for me to tell gcc/cpp to run
the preprocessor, but do nothing more than remove the
code which would not be present after if/ifdef/ifndef?
I can do "gcc -E" but that expands macros, puts line
numbers in, etc.


Larry

Re: Preprocess, but do not expand macros?

[Gokhan Kisacikoglu]

Well the macros, namely "define" statements, are part of the
preprocessor directives. I never heard of the execution of the
preprocessor directives partially in the way you describe...

Gokhan

Larry Riedel wrote:
> 
> Is there a simple way for me to tell gcc/cpp to run
> the preprocessor, but do nothing more than remove the
> code which would not be present after if/ifdef/ifndef?
> I can do "gcc -E" but that expands macros, puts line
> numbers in, etc.
> 
> Larry

Re: Preprocess, but do not expand macros?

[Larry Riedel]

> > Is there a simple way for me to tell gcc/cpp to run
> > the preprocessor, but do nothing more than remove the
> > code which would not be present after if/ifdef/ifndef?
> 
> Well the macros, namely "define" statements, are part
> of the preprocessor directives. [...]

To clarify, I would want the #define directives to be
processed, since otherwise the if/ifdef/ifndef might
not be meaningfully evaluated.  I simply do not want
the symbols defined by the #defines to be expanded.

before:
    #define PI 3.14
    #ifdef PI
        a = PI
    #endif

after:
        a = PI

instead of:
        a = 3.14


Larry

RE: Preprocess, but do not expand macros?

[landauer]

> Is there a simple way for me to tell gcc/cpp to run
> the preprocessor, but do nothing more than remove the
> code which would not be present after if/ifdef/ifndef?

Not gcc nor cpp itself, but there is a tool out there in
some OS's that is called "unifdef".  It might be close
enough for your purposes.  You might want to search the
web to see whether it's available.

 -- Doug L.

Re: Preprocess, but do not expand macros?

[Larry Riedel]

> > Is there a simple way for me to tell gcc/cpp to run
> > the preprocessor, but do nothing more than remove the
> > code which would not be present after if/ifdef/ifndef?
> 
> Not gcc nor cpp itself, but there is a tool out there in
> some OS's that is called "unifdef".

I see.  Yes, in fact the comp.lang.c FAQ says something
about it... oops.  It looks like there is an unifdef in
the source for FreeBSD which may compile elsewhere too.


Larry