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From: swang@calma.UUCP
Newsgroups: net.lang.c
Subject: Block Initialization
Message-ID: <586@calma.UUCP>
Date: Wed, 8-Oct-86 16:14:24 EDT
Article-I.D.: calma.586
Posted: Wed Oct  8 16:14:24 1986
Date-Received: Fri, 10-Oct-86 07:40:44 EDT
Reply-To: swang@calma.UUCP (Sin-Yaw Wang)
Distribution: na
Organization: GE/Calma Co., R&D Systems Engineering, Milpitas, CA
Lines: 50


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What is the most suitable (fast and portable among versions of Unix)
way to do block initialization?

Say I have a big structure of close to 4 Kbytes.
	
	typedef  struct {
		....
		....
	    } bigstruct;

	sizeof(bigstruct) == 4 +/- 10 Kbytes 

The details of this structure is too long, complicated and tedious to
duplicate here.  Its size may not be exactly 4Kb.

The chore is to initialize the entire structure to zero.  How do I do it?

One possible way is a function zero():

	main()
	{
		bigstruct p;
		zero((char *)&p);
	}
	zero(p)	char *p;	/* NOTE THE TYPE */
	{
		register int i = sizeof(bigstruct);
		while (i--) *p++ = 0;
	}

Another being a library call bzero()

	main()
	{
		bigstruct p;
		bzero(&p, sizeof(p));
	}

Is bzero() the optimum for this purpose for all Unix machines?
Is it portable, the Vax version is written in assembly?


I appreciate e-mailing opinions to me.

UUCP: ucbvax!calma!swang

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