auto_ptr to char[ size_t]?

[Marc Schellens]

I want to use an auto_ptr to a buffer:

auto_ptr<char> buffer = new char[ size];

But this does not work, as auto_ptr calls
delete instead of delete[], right?

What I can do? Is there a version of auto_ptr calling delete[]?

thanks,
marc

[tf]

Re: auto_ptr to char[ size_t]?

Marc Schellens wrote:[color=blue]
> I want to use an auto_ptr to a buffer:
>
> auto_ptr<char> buffer = new char[ size];
>
> But this does not work, as auto_ptr calls
> delete instead of delete[], right?[/color]

Right
[color=blue]
> What I can do? Is there a version of auto_ptr calling delete[]?
>
> thanks,
> marc[/color]

Use std::vector or std::string instead.
If you insist on using a smart pointer look
into the boost smart pointers www.boost.org

[John Harrison]

Re: auto_ptr to char[ size_t]?


"Marc Schellens" <m_schellens@ho tmail.com> wrote in message
news:3F1558F8.9 050706@hotmail. com...[color=blue]
> I want to use an auto_ptr to a buffer:
>
> auto_ptr<char> buffer = new char[ size];
>
> But this does not work, as auto_ptr calls
> delete instead of delete[], right?
>
> What I can do? Is there a version of auto_ptr calling delete[]?
>
> thanks,
> marc
>[/color]

You could go to your auto_ptr header (its in <memory> if memory serves!),
cut and paste the code into your editor (don't forget the copyright
message). Rename the class, and replace delete with delete[].

john

[Marc Schellens]

Re: auto_ptr to char[ size_t]?

>>I want to use an auto_ptr to a buffer:[color=blue][color=green]
>>
>>auto_ptr<char > buffer = new char[ size];
>>
>>But this does not work, as auto_ptr calls
>>delete instead of delete[], right?[/color]
>
>
> Right
>
>[color=green]
>>What I can do? Is there a version of auto_ptr calling delete[]?
>>
>>thanks,
>>marc[/color]
>
>
> Use std::vector or std::string instead.
> If you insist on using a smart pointer look
> into the boost smart pointers www.boost.org[/color]

I want to do ostream.write(c har*,count) for the string
(unformatted), therefore vector or string are no options here.

[Marc Schellens]

Re: auto_ptr to char[ size_t]?

>>>>I want to use an auto_ptr to a buffer:[color=blue][color=green][color=darkred]
>>>>
>>>>auto_ptr<ch ar> buffer = new char[ size];
>>>>
>>>>But this does not work, as auto_ptr calls
>>>>delete instead of delete[], right?
>>>
>>>
>>>Right
>>>
>>>
>>>
>>>>What I can do? Is there a version of auto_ptr calling delete[]?
>>>>
>>>>thanks,
>>>>marc
>>>
>>>
>>>Use std::vector or std::string instead.
>>>If you insist on using a smart pointer look
>>>into the boost smart pointers www.boost.org[/color]
>>
>>I want to do ostream.write(c har*,count) for the string
>>(unformatted) , therefore vector or string are no options here.[/color]
>
>
> Why is a std::vector<cha r> no option?
> You can provide its constructor the initial size,
> and use the pointer to its first element as the parameter
> in your function call.
>[/color]
Ok, I will do that.
Thanks,
marc

[DarkSpy]

Re: auto_ptr to char[ size_t]?

Marc Schellens <m_schellens@ho tmail.com> wrote in message news:<3F1558F8. 9050706@hotmail .com>...[color=blue]
> I want to use an auto_ptr to a buffer:
>
> auto_ptr<char> buffer = new char[ size];
> But this does not work, as auto_ptr calls[/color]

auto_ptr<char> buffer(new char[size]);
the ctor is explicit to force to write it.
[color=blue]
> delete instead of delete[], right?
>
> What I can do? Is there a version of auto_ptr calling delete[]?
>[/color]
delete included in dtor of auto_ptr.
[color=blue]
> thanks,
> marc[/color]

[John Harrison]

Re: auto_ptr to char[ size_t]?


"DarkSpy" <coneos@21cn.co m> wrote in message
news:aacb0456.0 307170049.56856 bcc@posting.goo gle.com...[color=blue]
> Marc Schellens <m_schellens@ho tmail.com> wrote in message[/color]
news:<3F1558F8. 9050706@hotmail .com>...[color=blue][color=green]
> > I want to use an auto_ptr to a buffer:
> >
> > auto_ptr<char> buffer = new char[ size];
> > But this does not work, as auto_ptr calls[/color]
>
> auto_ptr<char> buffer(new char[size]);
> the ctor is explicit to force to write it.
>[color=green]
> > delete instead of delete[], right?
> >
> > What I can do? Is there a version of auto_ptr calling delete[]?
> >[/color]
> delete included in dtor of auto_ptr.
>[/color]

Yes but the point is that using delete on a pointer that you created with
new[] invokes undefined behaviour. auto_ptr cannot be used with arrays.

john

[Russell Hanneken]

Re: auto_ptr to char[ size_t]?

"tf" <abc@abc.com> wrote in message
news:bf5k51$b7h jj$1@ID-57289.news.uni-berlin.de...[color=blue]
> Marc Schellens wrote:[color=green]
> > I want to do ostream.write(c har*,count) for the string
> > (unformatted), therefore vector or string are no options here.[/color]
>
> Why is a std::vector<cha r> no option?
> You can provide its constructor the initial size,
> and use the pointer to its first element as the parameter
> in your function call.[/color]

If I recall correctly, there's no guarantee that std::vector stores its
elements in an array. So in theory, that solution might not work. I admit
that, realistically, every implementation of std::vector probably does use
an array.

In any case, wouldn't the more natural solution be to store the characters
in a std::string, and then invoke std::string's data() member function to
get a character array when it's needed?

Regards,

Russell Hanneken
rhanneken@pobox .com

[Karl Heinz Buchegger]

Re: auto_ptr to char[ size_t]?



Russell Hanneken wrote:[color=blue]
>
> "tf" <abc@abc.com> wrote in message
> news:bf5k51$b7h jj$1@ID-57289.news.uni-berlin.de...[color=green]
> > Marc Schellens wrote:[color=darkred]
> > > I want to do ostream.write(c har*,count) for the string
> > > (unformatted), therefore vector or string are no options here.[/color]
> >
> > Why is a std::vector<cha r> no option?
> > You can provide its constructor the initial size,
> > and use the pointer to its first element as the parameter
> > in your function call.[/color]
>
> If I recall correctly, there's no guarantee that std::vector stores its
> elements in an array. So in theory, that solution might not work. I admit
> that, realistically, every implementation of std::vector probably does use
> an array.[/color]

The concensus is this:

* There is no guarantee
* This has probably been an oversight while comming up with the standard
* The next version of the standard will guarantee this
* It is hard or impossible to fullfill the requirements of std::vector
if the data is not stored contigous
* There is no known version which does not store the data contigous.
[color=blue]
>
> In any case, wouldn't the more natural solution be to store the characters
> in a std::string, and then invoke std::string's data() member function to
> get a character array when it's needed?[/color]

Could be. But a character pointer is often used to denote simply
a sequence of bytes. Not necessarly text.

--
Karl Heinz Buchegger
kbuchegg@gascad .at