TITLE: converting STL list to built-in array

(Newsgroups: comp.lang.c++, 21 Oct 98)


GREENFIELD: Pavel Greenfield

> >Is there an built-in way to convert a list<T> to an array (T *)?


PHLIP: Phlip <see@web.page>

> What about this?
>
>     T anArray [anArrayEXTENT];
>     list<T>::iterator it (yourList.begin ());
>
>     copy (anArray, anArray + anArrayEXTENT, it);
>
> I don't feel like compiling it, so I turned the Subject line back into a
> question.


KOENIG: ark@research.att.com (Andrew Koenig)

This example has a common bug: Generic algorithms such as copy do not act
on containers, but only on container elements.  Therefore, they cannot change
the size of the destination container.  Presumably yourList doesn't have the
right number of elements to begin with, so the call to copy will run off the
end of the list.

If you want to use copy this way, do something like

	copy (anArray, anARray + anArrayEXTENT, back_inserter(yourList));

Of course, this doesn't answer the original question, which was how
to go in the other direction.  Here's an example:

	T* array_ptr = new T[yourList.size()];
	copy(yourList.begin(), yourList.end(), array_ptr);