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rotate_copy


Category: algorithms 
Component type: function 
Prototype
template <class ForwardIterator, class OutputIterator>
OutputIterator rotate_copy(ForwardIterator first, ForwardIterator middle,
ForwardIterator last, OutputIterator result);
Description
Rotate_copy copies elements from the range [first, last) to the
range [result, result + (last  first)) such that *middle is
copied to *result, *(middle + 1) is copied to *(result + 1), and
so on. Formally, for every integer n such that 0 <= n < last 
first, rotate_copy performs the assignment *(result + (n + (last 
middle)) % (last  first)) = *(first + n). Rotate_copy is similar
to copy followed by rotate, but is more efficient. The
return value is result + (last  first).
Definition
Defined in the standard header algorithm, and in the nonstandard
backwardcompatibility header algo.h.
Requirements on types

ForwardIterator is a model of Forward Iterator.

OutputIterator is a model of Output Iterator.

ForwardIterator's value type is convertible to a type in
OutputIterator's set of value types.
Preconditions

[first, middle) is a valid range.

[middle, last) is a valid range. [1]

There is enough space to hold all of the elements being copied.
More formally, the requirement is that
[result, result + (last  first)) is a valid range.

The ranges [first, last) and [result, result + (last  first))
do not overlap.
Complexity
Linear. Rotate_copy performs exactly last  first assignments.
Example
const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
rotate_copy(alpha, alpha + 13, alpha + 26, ostream_iterator<char>(cout));
// The output is nopqrstuvwxyzabcdefghijklm
Notes
[1]
It follows from these two requirements that [first, last) is
a valid range.
See also
rotate, copy.
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