Terminology

[Ray Mitchell]

Here's a question to reflect my misunderstanding of some basic terminology.
Upon looking for a concise, English definition of the term "expression" in
a multitiude of C texts, the best I can come up with is:

	"Any combination of constants, variables, and operators
	 (producing a value)"

I put "producing a value" in parentheses because therein lies my problem.  It
seems intuitively clear that an expression must have a value and it follows
that a function returning a value qualifies as an expression.  However, how
about a function returning "void" or an expression cast to type "void"?  Are
these two cases no longer considered to be expressions or is "void" considered
to be a value for the sake of the definition of an expression?

Ray Mitchell