Question

I need a macro to expand to a c++ comment, is that possible?

I’ve got this:

#define SLASH(x,y) x y
#define OUT SLASH(/,/)

int main(int argc, char *argv[])
{
  OUT << "text";
  return 0;
}

And need to expand to this:

{
  // << "text";
  return 0;
}

I’ve also tried this:

#define SLASH(x) /x
#define OUT SLASH(/)

But the result is still the same:

int main(int argc, char *argv[])
{
  / / << "text";
  return 0;
}

Answer 1

As others mentioned there is no guaranteed way to define the kind of macro you are looking for. Other ways to achieve results that are similar to what you seem to be trying to achieve are wrapping your output statement in a conditional block or define a custom output stream that just discarded all output. The two approaches may even be combined so that behaviour could be switched by changing a single macro definition.