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From: gwyn@BRL.ARPA (VLD/VMB)
Newsgroups: net.lang.c
Subject: Re:  Uses of \"short\" ?
Message-ID: <3241@brl-tgr.ARPA>
Date: Fri, 15-Nov-85 02:14:33 EST
Article-I.D.: brl-tgr.3241
Posted: Fri Nov 15 02:14:33 1985
Date-Received: Sat, 16-Nov-85 09:50:27 EST
Sender: news@brl-tgr.ARPA
Lines: 35

Your note reminded me of something I wanted to comment on.
I have observed a lot of C code that tries converting back
and forth between data types (using type casts) with wild
abandon.  This is symptomatic of a program out of control.
Using appropriate data types in a straight-forward fashion
results in code containing very few type casts.  The main
uses I have for type casts fall into a few categories:

	(void) to discard the return value of a function;
	this should be not be done without thinking about
	the appropriateness of ignoring the return value.
	I do this mainly for fprintf(stderr,...), since
	usually I can't think of anything better to do if
	that function call fails.

	Casting the returned value from malloc() (also the
	argument to free()).  This should be obvious.

	Forcing a short or an int to become a long, as in
		i = j * (long)k / l;
	to avoid numeric overflow.

	Truncating a floating-point quantity to its integer
	part (warning! not the same as the floor() function).

	Passing a NULL pointer argument to a function.

	Documenting a coercion that will occur anyhow, as
	in passing a (char) as a function argument or in
	certain assignments, when it is important to
	realize that this is happening.

There are some other instances where casts are useful, but
they should be used sparingly and not as a substitute for
declaring data types properly.