Is there a good example of how toupper() works?

[Doug Gwyn]

In article <1990Nov12.040933.5419 at sq.sq.com> msb at sq.sq.com (Mark Brader) writes:
>Now, isascii() itself is not in ANSI C.

It doesn't need to be.  All values of unsigned char, as well as EOF,
work just fine as is*() arguments.