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From: dougm@zamenhof.rice.edu (Doug Moore)
Newsgroups: comp.lang.c++
Subject: operator []: ref vs value
Message-ID: <5216@brazos.Rice.edu>
Date: 22 Feb 90 16:36:38 GMT
Sender: root@rice.edu
Organization: Rice University, Houston
Lines: 12


I can't seem to find a way to do precisely what I want; I want a
sparse vector data type.  I can declare a float-returning operator []
that returns 0.0 if the array index corresponds to a row for which no
nonzero is stored.  I can declare a reference-to-float-returning
operator[] that creates a new entry in my linked list of nonzero
values when the row has no corresponding nonzero stored.
Unfortunately, I want one behavior when the pseudo-array access occurs
as an rvalue and another when it appears as an lvalue.  Can I get what
I want?

Dougm