Aztec C on the Apple ][ is a sorry, lazy,
flea-ridden dog.
Any C implementation for that era (1979) of micros is a
pretty good find, IMHO.
I remember running OS-9 C on my CoCo. It wasn't a bad language, actually,
but it had to load the compiler in about 3 sections from disk (the
preprocessor, section 1 and section 2 IIRC), and wrote all sorts of
temporary files between sections. I didn't have a hard disk, so it took a
long time to compile anything, loading each bit from floppies...
Although I'd reccomend finding a C for the PC
class, post
8086, (1985+) if what you want to learn is software.
If you want to learn C, install one of the free unices and run gcc. Oh,
and buy K&R -- you'll be glad you did. I couldn't understand any of the
'learn C in 2 weeks' type of books, I thoguht C was well beyond me. Then
I bought K&R and was writing simple programs the same afternoon. K&R is
expensiver per page I guess (it's a thin book), but it's full of
information, and it's logically set out.
-tony