Question

I have

#define ADD 5
#define SUB 6

Can I print ADD and SUB given their values 5 and 6?

Answer 1

No.

The names of the defined symbols are removed by the preprocessor, so the compiler never sees them.

If these names are important at runtime, they need to be encoded in something more persistent than just preprocessor symbol names. Perhaps a table with strings and integers:

#define DEFINE_OP(n) { #n, n }

static const struct {
  const char *name;
  int        value;
} operators[] = {
  DEFINE_OP(ADD),
  DEFINE_OP(SUB),
};

This uses the stringifying preprocessor operator # to avoid repetitions.

With the above, you can trivially write look-up code:

const char * op_to_name(int op)
{
  size_t i;

  for(i = 0; i < sizeof operators / sizeof *operators; ++i)
    if(operators[i].value == op)
      return operators[i].name;
  return NULL;
}