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From: ahodgson@athena.mit.edu (Antony Hodgson)
Newsgroups: comp.lang.c++
Subject: Re: Matrix Class Libraries
Message-ID: <1991Mar21.151635.21044@athena.mit.edu>
Date: 21 Mar 91 15:16:35 GMT
References: <1991Mar18.025539.18998@athena.mit.edu> <ARI.HUTTUNEN.91Mar18173446@hydroman.hut.fi> <6732@celery34.UUCP>
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In article <6732@celery34.UUCP> stephens@motcid.UUCP (Kurt Stephens) writes:
>Ari.Huttunen@hut.fi (Ari Juhani Huttunen) writes:

stuff about how he wants to use [][] to get access to matrix elements
rather than (int,int).
>
>Just define:
>
>inline
>double*
>Matrix::operator [](int i) { return Row(i); }
>
>Matrix M;
>double d;
>
>	d = M[1][2];
>
>"M[1]" evals to a double*, right?  The "[2]" indexes off the double*.
>KISS (Keep It Simple Stephens) ;^)
>
In this case, the solution is too simple.  The problem with returning
a double* is that you can no longer perform bounds checking on the second
index (the index i in operator[] should really be checked for validity as
well).  Of course, if you don't want to do bounds checking, this solution
is fine.

Tony Hodgson
ahodgson@hstbme.mit.edu