The return value is result + n.
Definition Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h. This function is an SGI extension; it is not part of the C++ standard.
Requirements on types • InputIterator is a model of Input Iterator.
• OutputIterator is a model of Output Iterator.
• Size is an integral type.
• InputIterator's value type is convertible to a type in OutputIterator's set of value types.
Preconditions • n >= 0.
• [first, first + n) is a valid range.
• result is not an iterator within the range [first, first + n) .
• [result, result + n) is a valid range.
Complexity Linear. Exactly n assignments are performed.
Example vector<int> V(5);
iota(V.begin(), V.end(), 1);
list<int> L(V.size());
copy_n(V.begin(), V.size(), L.begin());
assert(equal(V.begin(), V.end(), L.begin()));
Notes [1] Copy_n is almost, but not quite, redundant. If first is an input iterator, as opposed to a forward iterator, then the copy_n operation can't be expressed in terms of copy.
See also copy, copy_backward
Category: algorithms
Component type: function
Prototype template <class BidirectionalIterator1, class BidirectionalIterator2>
BidirectionalIterator2 copy_backward(BidirectionalIterator1 first, BidirectionalIterator1 last, BidirectionalIterator2 result);
Description Copy_backward copies elements from the range [first, last) to the range [result – (last – first), result) [1]. That is, it performs the assignments *(result – 1) = *(last – 1), *(result – 2) = *(last – 2) , and so on. Generally, for every integer n from 0 to last – first, copy_backward performs the assignment *(result – n – 1) = *(last – n – 1). Assignments are performed from the end of the input sequence to the beginning, i.e. in order of increasing n. [2]
The return value is result – (last – first)
Definition Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h.
Requirements on types • BidirectionalIterator1 and BidirectionalIterator2 are models of BidirectionalIterator.
• BidirectionalIterator1's value type is convertible to BidirectionalIterator2's value type.
Preconditions • [first, last) is a valid range.
• result is not an iterator within the range [first, last) .
• There is enough space to hold all of the elements being copied. More formally, the requirement is that [result – (last – first), result) is a valid range.
Complexity Linear. Exactly last – first assignments are performed.
Example vector<int> V(15);
iota(V.begin(), V.end(), 1);
copy_backward(V.begin(), V.begin() + 10, V.begin() + 15);
Notes [1] Result is an iterator that points to the end of the output range. This is highly unusual: in all other STL algorithms that denote an output range by a single iterator, that iterator points to the beginning of the range.
[2] The order of assignments matters in the case where the input and output ranges overlap: copy_backward may not be used if result is in the range [first, last). That is, it may not be used if the end of the output range overlaps with the input range, but it may be used if the beginning of the output range overlaps with the input range; copy has opposite restrictions. If the two ranges are completely nonoverlapping, of course, then either algorithm may be used.
See also copy, copy_n
Category: algorithms
Component type: function
Prototype template <class Assignable>
void swap(Assignable& a, Assignable& b);
Description Assigns the contents of a to b and the contents of b to a. This is used as a primitive operation by many other algorithms.
Definition 
