Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.lang.c
Subject: Re: a style question
Message-ID: <3376:Oct2320:51:5590@kramden.acf.nyu.edu>
Date: 23 Oct 90 20:51:55 GMT
References: <2039@excelan.COM> <443@mole-end.UUCP> <1990Oct23.160116.10299@athena.mit.edu>
Organization: IR
Lines: 20

In article <1990Oct23.160116.10299@athena.mit.edu> tada@athena.mit.edu (Michael J Zehr) writes:
>     v = (a[i-1][j-1] + a[i][j-1] + a[i-1][j+i] +
>          a[i-1][j] + a[i][j] + a[i-1][j+1] +
>          a[i-1][j+1] + a[i][j-1] + a[i-1][j+1])/9;

At a minimum I'd format this as

      v = (a[i-1][j-1] + a[i][j-1] + a[i-1][j+i] +
	   a[i-1][j  ] + a[i][j  ] + a[i-1][j+1] +
	   a[i-1][j+1] + a[i][j-1] + a[i-1][j+1])/9

which makes the j + i pretty obvious. Or a macro:

#define A(b,c) a[i+(b)][j+(c)]
      v = ( A(-1,-1) + A(0,-1) + A(-1,+i) +
	    A(-1, 0) + A(0, 0) + A(-1,+1) +
	    A(-1,+1) + A(0,-1) + A(-1,+1) ) / 9
#undef A

---Dan