partial preprocessing

[Theron Stanford]

I've inherited a bunch of code that contains a lot of conditional
preprocessing commands.

Is there a way to run the preprocessor so that it processes the
conditionals but leaves the rest of the macros alone?

Take this code for an example:

/* start of code */

#define CONSTANT1 1
#define CONSTANT2 2

#if defined (A)
x = CONSTANT1;
#endif

#if defined (B)
x = CONSTANT2;
#endif

/*end of code */

I'd like to invoke the preprocessor with

cpp -DA

(and perhaps another option or two) and get back

/* start of code */

#define CONSTANT1 1
#define CONSTANT2 2

x = CONSTANT1;

/* end of code */

Since the #defined macros have useful names, I don't want them being
replaced by their values, namely:

/* start of code */

x = 1;

/* end of code */

Thanks in advance.

Theron

 

[Eric Sosman]

I've inherited a bunch of code that contains a lot of conditional
preprocessing commands.

Is there a way to run the preprocessor so that it processes the
conditionals but leaves the rest of the macros alone?

This is Question 10.18 in the comp.lang.c Frequently
Asked Questions (FAQ) list

http://www.eskimo.com/~scs/C-faq/top.html

 

[Theron Stanford]

This is Question 10.18 in the comp.lang.c Frequently
Asked Questions (FAQ) list

http://www.eskimo.com/~scs/C-faq/top.html

Apologies all around. I went through that section of the FAQ, but
obviously not thoroughly enough.

Theron