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From: RayeR <glaux AT centrum DOT cz>
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Subject: Re: Upgrading from a bad C compiler
Date: Thu, 26 Jul 2012 18:23:51 -0700 (PDT)
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> I&#39;d assume alignment would increase the physical size.  I don&#39;t know if it
> increases sizeof()&#39;s value though.  I would think not...  I would think that
> C should only return the total size for C elements and not padding or
> alignment.

No, sizeof() is called on a structure which is aligned by default it returns total size including padding bytes! Usually 8bit members are extended to 16bits to be placed on even address. If you need a srtucture that match exact size (e.g. reading some header from file to struct in memory) use __attribute__ ((packed)). Then sizeof will return number that is exact sum of all members size.