A cascade of macros is when one macro's body contains a reference to another macro. This is very common practice. For example,
#define BUFSIZE 1020 #define TABLESIZE BUFSIZE
This is not at all the same as defining `TABLESIZE' to be `1020'. The `#define' for `TABLESIZE' uses exactly the body you specify--in this case, `BUFSIZE'---and does not check to see whether it too is the name of a macro.
It's only when you use `TABLESIZE' that the result of its expansion is checked for more macro names.
This makes a difference if you change the definition of `BUFSIZE' at some point in the source file. `TABLESIZE', defined as shown, will always expand using the definition of `BUFSIZE' that is currently in effect:
#define BUFSIZE 1020 #define TABLESIZE BUFSIZE #undef BUFSIZE #define BUFSIZE 37
Now `TABLESIZE' expands (in two stages) to `37'. (The
`#undef' is to prevent any warning about the nontrivial