Newsgroups: comp.os.msdos.djgpp
From: pjbk AT cee DOT hw DOT ac DOT uk (Peter JB King)
Subject: Re: C++ class interaction and overloading (should be simple answer)
Message-ID: <EEFqM8.Hr1@cee.hw.ac.uk>
Sender: news AT cee DOT hw DOT ac DOT uk (News Administrator)
Organization: Dept of Computing & Electrical Engineering, Heriot-Watt University, Scotland
References: <33E3B107 DOT 63DEA07F AT execulink DOT com>
Date: Tue, 5 Aug 1997 10:03:43 GMT
Lines: 33
To: djgpp AT delorie DOT com
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In article <33E3B107 DOT 63DEA07F AT execulink DOT com> Jeff Weeks <pweeks AT execulink DOT com> writes:
>Hi there...
>
>I've got a C++ problem here.  I've defined a two classes: Vector and
>Matrix.  I'd like to be able to do this:
>
>Vector2 = Vector1 * Matrix1
>
>But I can't get that to work.  Is this possible?
>
>What I tried was this (in my Vector class):
>
>class Vector {
>  ...
>  public:
>    inline friend Vector operator * (Matrix& mat, Vector& vect);
>  ...
>};
...
>I'm afraid I can't remember the error I got (and I'm in Linux now so I
>can't check...).  It was something along the lines of, "Can't find
>operator to math that expression" :)
>

The problem is that you have defined an operator for 
Matrix * Vector,
not one for 
Vector * Matrix.
-- 
Peter King, Computing & Electrical Eng.	 Internet: pjbk AT cee DOT hw DOT ac DOT uk
  Heriot-Watt University, Riccarton,      or  P DOT J DOT B DOT King AT heriot-watt DOT ac DOT uk
  Edinburgh EH14 4AS, Scotland
Phone: (+44) 131 451 3433               Fax: (+44) 131 451 3431