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2039. Issues withstd::reverse andstd::copy_if

Section: 26.7.1[alg.copy], 26.7.10[alg.reverse]Status:C++14Submitter: Nikolay IvchenkovOpened: 2011-03-02Last modified: 2016-01-28

Priority:Not Prioritized

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Discussion:

1. In the description ofstd::reverse

   Effects: For each non-negative integeri <= (last - first)/2, appliesiter_swap to all pairs of iteratorsfirst + i,(last - i) - 1.

   should be changed to

   Effects: For each non-negative integeri< (last - first)/2, appliesiter_swap to all pairs of iteratorsfirst + i,(last - i) - 1.

   Herei shall be strictly less than(last - first)/2.

2. In the description ofstd::copy_ifReturns paragraph is missing.

[2011-03-02: Daniel drafts wording]

Proposed resolution:

1. Modify 26.7.10[alg.reverse] p. 1 as indicated:

   1Effects: For each non-negative integeri <= (last - first)/2, appliesiter_swap to all pairs of iteratorsfirst + i,(last - i) - 1.

2. Add the followingReturns element after 26.7.1[alg.copy] p. 9:

   template<class InputIterator, class OutputIterator, class Predicate>OutputIterator copy_if(InputIterator first, InputIterator last,   OutputIterator result, Predicate pred);

   8Requires: The ranges[first,last) and[result,result + (last - first)) shall not overlap.

   9Effects: Copies all of the elements referred to by the iteratori in the range[first,last) for whichpred(*i) is true.

   ??Returns: The end of the resulting range.

   10Complexity: Exactlylast - first applications of the corresponding predicate.

   11Remarks: Stable.