[LC++]STL and auto_ptr woes

[Charles Randle]

Thanks for the info , I tried the suggestion it appears to have removed 
error.
Once again , THANKS !

Best Regards,
Charles Randle


>From: "George T. Talbot" <george at phat.com>
>To: <tuxcpprogramming at lists.linux.org.au>, <charlesrandle at hotmail.com>
>Subject: Re: [LC++]STL and auto_ptr woes
>Date: Wed, 6 Mar 2002 09:39:48 -0500
>
>I don't think that auto_ptr<> supports the assignment operator--it only
>supports initialization via the constructor.  That's why it won't work in
>your scenario.
>
>Change that line to read like this:
>
>::std::auto_ptr<someobject1> vb(BigMap2["located"].second.first);
>
>That should get rid of the compile error.  However, this will fail 
>horribly.
>When vb goes out of scope, the object will be freed.  Then you'll have a
>dangling pointer in your list and your program will crash later when that
>item in the list is accessed or freed.
>
>Is auto_ptr<> supposed to work in a Standard C++ Library collection?  I 
>seem
>to recall this as being a no-no, but I don't have the book in front of me
>right now.
>
>--George
>
>P.S.  The list seems to be operating pretty slow.  I just received this at
>about 9:35am EST on the 6th, and it was sent on the 4th and 2:45pm.
>
>
>
>----- Original Message -----
>From: "Charles Randle" <charlesrandle at hotmail.com>
>To: <tuxcpprogramming at lists.linux.org.au>
>Sent: Monday, March 04, 2002 2:45 PM
>Subject: [LC++]STL and auto_ptr woes
>
>
> > Hi All ,
> >
> > I am using the STL to store pointers to objects which are expensive to
>copy
> > (hence the pointers.
> >
> > I know it isn't a good idea to use the auto_ptr class with STL classes 
>but
>I
> > don't readily remember why could anyone tell me why the following 
>wouldn't
> > be a good idea ?
> >
> > ::std::map <
> > ::std::string,::std::pair<auto_ptr<someobject1>,auto_ptr<someobject2> > 
> >
> > bigMap;
> >
> > Given that the above isn't a good idea I have the following:
> >
> > ::std::map < ::std::string , ::std::pair<someobject1 *,someobject2 *> >
> > BigMap2
> >
> > However when I assign the pointers to an auto_ptr object as in:
> >
> > ::std::auto_ptr<someobject1> vb = BigMap2["located"].second.first;
> >
> > the compiler gives the following error:
> >
> > simple.cpp:52:conversion from 'someobject1*' to non-scalar type
> > 'std::auto_ptr<someobject1>' requested
> >
> >
> > What is the reason for this error and what can I do to fix it ???
> >
> >
> > Best Regards,
> > Charles Randle
> >
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> > _______________________________________________
> > This is the Linux C++ Programming List
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> >
>




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