Article View: comp.std.c
Article #1892Re: Another sizeof question
From: Yiannis Papelis
Date: Sun, 28 Oct 1990 17:57
Date: Sun, 28 Oct 1990 17:57
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1228 bytes
In article <13171@crdgw1.crd.ge.com> volpe@camelback.crd.ge.com (Christopher R Volpe) writes: >Can someone tell me whether "sizeof" expressions are allowed as >operands of "#if"? I'm trying to do some conditional compilation >based on the size of some data structure, and I get parse errors >before sizeof. The Bible says "sizeof" yields a constant integer, >and that #if requires an integral constant expression, so I can't >tell what's wrong. Can someone clue me in? Thanks. > >BTW, I'm using gcc to compile. > sizeof expressions 'become' a constant integer at compile time. In other words only the compiler knows what sizeof(whatever) is. Since the preproccessor runs before the compiler it has no way of knowing the value of sizeof. Yiannis E. Papelis Department of Electrical and Computer Engineering, University of Iowa. yiannis@eng.uiowa.edu
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!ns-mx!ccad.uiowa.edu!yiannis From: yiannis@ccad.uiowa.edu (Yiannis Papelis) Newsgroups: comp.std.c Subject: Re: Another sizeof question Message-ID: <1990Oct28.175729.23696@ccad.uiowa.edu> Date: 28 Oct 90 17:57:29 GMT References: <13171@crdgw1.crd.ge.com> Organization: CAD-Research, U. of Iowa, Iowa City, Iowa Lines: 19