How to get the definition of a macro as a string literal?

Question

Say in a header, which I do not want to read myself but which I do include, I have

#define A B
#define B C

Now

#define STR(name) # name

defines a macro that gives me the name of any macro as a string, and

#define EXP_STR(name) STR(name)

defines a macro that gives me the full expansion of any macro as a string. So

cout << STR(A) << EXP_STR(A) << endl;

will print AC.

Is there any way to get "B" from A using some macros?

Answer 1

Since you can write

#define B C
#define A B

#define STR(name) # name
#define EXP_STR(name) STR(name)

and the

cout << STR(A) << EXP_STR(A) << endl;

will output exaclty the same, it means that it's not possible.

When you do this

#define A B

and then

#define B C

now this means that A will be substituted by C and not B, so there will be no way to do it because when the cout line is reached the preprocessor had already substituted A by C.

So the short answer is, it's not possible because the preprocessor would have replaced A with C before the file is compiled.