stupid C preprocessor question

[Steven G. Kargl]

I learned K&R C several years ago and now have a need
to return to programming in C.  Is the following legal C?

#include <math.h>
double tmp(void) {
   double x;
   x = sin(1.);
#if 0
   Can't do this
#endif
   return x;
}

-- 
Steve
http://troutmask.apl.washington.edu/~kargl/