Newsgroups: comp.lang.c
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: sizeof() confusion
Message-ID: <1990Nov17.041345.7158@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <2665@cirrusl.UUCP> <2692@cirrusl.UUCP> <1990Nov14.154213.27324@cbnewsj.att.com> <14462@smoke.brl.mil> <1990Nov16.141352.22426@dce.ie>
Date: Sat, 17 Nov 90 04:13:45 GMT

In article <1990Nov16.141352.22426@dce.ie> ch@dce.ie (Charles Bryant) writes:
>> there are two distinct uses of sizeof:
>>	sizeof unary_expression
>>	sizeof ( type_name )
>
>That must make parsing it more difficult than if the parentheses were always
>required:
>	sizeof (type_name) - 1
>since in other contexts "(type_name) - 1" would be an expression containing
>a cast.

Requiring parentheses wouldn't make any difference, since it's still legal
to wrap a unary expression in parentheses, so you can't tell from the
opening parenthesis which form is coming.  What *would* be useful is if
casts began with something that *couldn't* begin a unary expression.
As it is, either you need to sneak a peek a bit further ahead, or you
get to write some contorted code that swallows the parenthesis and then
decides, based on the next token, whether it has cast-minus-leading-paren
or parenthesized-expression-minus-leading-paren.  Definitely a nuisance,
and it's not the only such case in C.
-- 
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  henry@zoo.toronto.edu   utzoo!henry