Is there a way to manipulate preprocessor define scope in C-CodePudding

Just curious. Imagine I need to have a #define A that is the sum of n numbers, and those n numbers have a meaning I'd like to make explicit, but only for the computation of A, to improve readiblity, instead of writing n macros or just writing #define A <result_of_the_sum>.
Is there a way I could limit the reach of these n #define directives to just the definition of A ? Just as in C one would do :

int a = 0;
{
int b = 1;
int c = 2;
int d = 3;
a = b   c   d;
} // end of b,c,d scope.

My intention is to have A defined when compiling but no definition for the other n defines used to compute A, since these would only be useful to understand the code better.
Edit:
Imagine I have these macros:

#define MEANINGFUL_NUMBER_1 1
#define MEANINGFUL_NUMBER_2 2
#define MEANINGFUL_NUMBER_3 3

And I have a macro, A that is the sum of them, and I like someone reading my code to understand the value of A not just see it defined straightforwardly, i.e. #define A (MEANINGFUL_NUMBER_1 ... MEANINGFUL_NUMBER_N), such that only A is substituted before compilation but MEANINGUL_NUMBER_* is not.

CodePudding user response：

Is there a way to manipulate preprocessor define scope in C

No.

Is there a way I could limit the reach of these n #define directives to just the definition of A ?

No.

Note that macros are evaulated upon use. That means that everything has to be visible when the macro is used. You can #undef all the macros after all usages, ergo "limit the reach" in that way.

In C, there are no namespaces. In C use prefixes. You would do:

#define LIB_PRIV_B  1
#define LIB_PRIV_C  2
#define LIB_PRIV_D  3
#define LIB_A  (LIB_PRIV_B   LIB_PRIV_C   LIB_PRIV_D)

If you really do not want the numbers to leak into C, then use something to generate the C source code, which also gives you more power to the preprocessor side. Use jinja2, m4, php or python, and configure your build system to properly handle the generation dependency.