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From: dave@cs.arizona.edu (Dave P. Schaumann)
Newsgroups: comp.lang.c
Subject: Re: Expressions in initializers
Message-ID: <1032@caslon.cs.arizona.edu>
Date: 5 Mar 91 02:39:25 GMT
References: <17270@crdgw1.crd.ge.com> <760@ajpo.sei.cmu.edu> <1991Mar4.144939.8311@ux1.cso.uiuc.edu>
Organization: U of Arizona CS Dept, Tucson
Lines: 24

In article <1991Mar4.144939.8311@ux1.cso.uiuc.edu> mcdonald@aries.scs.uiuc.edu (Doug McDonald) writes:
>sqrt(2.0) is an expression. It CAN be evaluated at compile time. Perhaps
>some people don't want to write compilers that do that (i.e. they are too
>lazy), but it most certainly CAN be evaluated.
>
>Perhaps a different explanation is appropriate?

You want to link the whole floating point library to the C compiler?

First thing you need to realize is that there is no special, pre-defined
function sqrt() in C.  (Suprise!!!)  The function sqrt lives in a link
libarary.  As far as the C compiler knows, it's just another user-defined
function.  So it can't really be evaluated at compile time.

That said, sqrt() (or any other linked-in or user defined function) is known
at run-time, so you could have static int foo = bar(baz) ; be short-hand for
an initialization that gets done before main() is called.  This is another
kettle of fish entirely, though.

-- 
		Dave Schaumann		dave@cs.arizona.edu
'Dog Gang'!  Where do they get off calling us the 'Dog Gang'?  I'm beginning to
think the party's over.  I'm beginning to think maybe we don't need a dog.  Or
maybe we need a *new* dog.  Or maybe we need a *cat*! - Amazing Stories