It's your choice. Preprocessor macros like TRUE and FALSE (and, of course,
NULL) are used for code readability, not because the underlying values might ever
change. It's a matter of style, not correctness, whether to use symbolic names
or raw 1/0 values.
On the one hand, using a symbolic name like TRUE or FALSE reminds the reader that
a Boolean value is involved. On the other hand, Boolean values and definitions can
evidently be confusing, and some programmers feel that TRUE and FALSE macros only
compound the confusion.