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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: net.lang.c
Subject: Re: Block Initialization
Message-ID: <4510@brl-smoke.ARPA>
Date: Fri, 10-Oct-86 11:26:02 EDT
Article-I.D.: brl-smok.4510
Posted: Fri Oct 10 11:26:02 1986
Date-Received: Sat, 11-Oct-86 06:54:18 EDT
References: <586@calma.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Distribution: na
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 27

In article <586@calma.UUCP> swang@calma.UUCP (Sin-Yaw Wang) writes:
>Say I have a big structure of close to 4 Kbytes.
>	
>	typedef  struct {
>		....
>		....
>	    } bigstruct;
>
>The chore is to initialize the entire structure to zero.  How do I do it?

The wrong way is to use bzero(), which fills a region with 0 bytes
and which exists only on Berkeley-based systems (System V/X3J11 use
memset()).  There are at least two problems with this:
	(1)  the struct padding may not be accessible on some architectures,
		so storing into it may cause a trap;
	(2)  0 bytes are not necessarily appropriate representations of the
		value zero for all data types, especially floating-point.

Try the following:

static bigstruct zero;	/* required to be initialized to 0s of proper types */

...

	bigstruct p;

	p = zero;	/* struct copy is optimized by compiler */