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1339. uninitialized_fill_n should return the end of its range

Section: 26.11.7 [uninitialized.fill] Status: C++11 Submitter: Jared Hoberock Opened: 2010-07-14 Last modified: 2017-06-15

Priority: Not Prioritized

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Discussion:

N3092's specification of uninitialized_fill_n discards useful information and is inconsistent with other algorithms such as fill_n which accept an iterator and a size. As currently specified, unintialized_fill_n requires an additional linear traversal to find the end of the range.

Instead of returning void, unintialized_fill_n should return one past the last iterator it dereferenced.

[ Post-Rapperswil: ]

Moved to Tentatively Ready after 5 positive votes on c++std-lib.

[ Adopted at 2010-11 Batavia ]

Proposed resolution:

In section 20.2 [memory] change:, 

template <class ForwardIterator, class Size, class T>
  void ForwardIterator uninitialized_fill_n(ForwardIterator first, Size n, const T& x);

In section [uninitialized.fill.n] change, 

template <class ForwardIterator, class Size, class T>
  void ForwardIterator uninitialized_fill_n(ForwardIterator first, Size n, const T& x);

1 Effects: 

for (; n--; ++first)
  ::new (static_cast<void*>(&*first))
    typename iterator_traits<ForwardIterator>::value_type(x);
return first;