Printing name and value of a macro

Question

I have a C program with a lot of optimizations that can be enabled or disabled with #defines. When I run my program, I would like to know what macros have been

Answer 1

Why not simply testing it with the preprocessor ?

 #if defined(X)
      printf("%s is defined and as the value %d\n", #X, (int)X);
 #else
      printf("%s is not defined\n", #X);
 #endif

One can also embed this in another test not to print it everytime:

 #if define(SHOW_DEFINE)
 #if defined(X)
      printf("%s is defined and as the value %d\n", #X, (int)X);
 #else
      printf("%s is not defined\n", #X);
 #endif
 #endif