The following comment was made by one of the amazon dot com engineers on my schools internal bbs system.
Which ctype functions is he talking about?The return value of malloc compares equal to zero upon failure.
The ctype functions return nonzero (true)
if and only if the value of the argument conforms to that
in the description of the function.
If you want the return value
to be able to indicate which mode of failure occured,
then that's when zero is the value to return for success.