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      std::rotate_copy

      From cppreference.com
      <cpp‎ |algorithm
       
       
      Algorithm library
      Constrained algorithms and algorithms on ranges(C++20)
      Constrained algorithms, e.g.ranges::copy,ranges::sort, ...
      Execution policies(C++17)
      Sorting and related operations
      Partitioning operations
      Sorting operations
      Binary search operations
      (on partitioned ranges)
      Set operations (on sorted ranges)
      Merge operations (on sorted ranges)
      Heap operations
      Minimum/maximum operations
      (C++11)
      (C++17)
      Lexicographical comparison operations
      Permutation operations
      C library
      Numeric operations
      Operations on uninitialized memory
       
      Defined in header<algorithm>
      template<class ForwardIt,class OutputIt>

      OutputIt rotate_copy( ForwardIt first, ForwardIt middle,

                            ForwardIt last, OutputIt d_first);
      (1)(constexpr since C++20)
      template<class ExecutionPolicy,

               class ForwardIt1,class ForwardIt2>
      ForwardIt2 rotate_copy( ExecutionPolicy&& policy,
                              ForwardIt1 first, ForwardIt1 middle,

                              ForwardIt1 last, ForwardIt2 d_first);
      (2)(since C++17)

      Copies theleft rotation of[firstlast) tod_first.

      1) Copies the elements from the range[firstlast), such that in the destination range beginning atd_first, the elements in[firstmiddle) are placed after the elements in[middlelast) while the orders of the elements in both ranges are preserved.
      2) Same as(1), but executed according topolicy.
      This overload participates in overload resolution only if all following conditions are satisfied:

      std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> istrue.

      (until C++20)

      std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>> istrue.

      (since C++20)

      If any of the following conditions is satisfied, the behavior is undefined:

      • [firstmiddle) or[middlelast) is not avalid range.
      • The source and destination ranges overlap.

      Contents

      [edit]Parameters

      first, last - the pair of iterators defining the sourcerange of elements to copy
      middle - an iterator to an element in[firstlast) that should appear at the beginning of the new range
      d_first - beginning of the destination range
      policy - theexecution policy to use
      Type requirements
      -
      ForwardIt, ForwardIt1, ForwardIt2 must meet the requirements ofLegacyForwardIterator.
      -
      OutputIt must meet the requirements ofLegacyOutputIterator.

      [edit]Return value

      Output iterator to the element past the last element copied.

      [edit]Complexity

      Exactlystd::distance(first, last) assignments.

      [edit]Exceptions

      The overload with a template parameter namedExecutionPolicy reports errors as follows:

      • If execution of a function invoked as part of the algorithm throws an exception andExecutionPolicy is one of thestandard policies,std::terminate is called. For any otherExecutionPolicy, the behavior is implementation-defined.
      • If the algorithm fails to allocate memory,std::bad_alloc is thrown.

      [edit]Possible implementation

      See also the implementations inlibstdc++,libc++, andMSVC STL.

      template<class ForwardIt,class OutputIt>constexpr// since C++20OutputIt rotate_copy(ForwardIt first, ForwardIt middle,                     ForwardIt last, OutputIt d_first){    d_first=std::copy(middle, last, d_first);returnstd::copy(first, middle, d_first);}

      [edit]Example

      Run this code
      #include <algorithm>#include <iostream>#include <iterator>#include <vector> int main(){std::vector<int> src{1,2,3,4,5};std::vector<int> dest(src.size());auto pivot=std::find(src.begin(), src.end(),3);     std::rotate_copy(src.begin(), pivot, src.end(), dest.begin());for(int i: dest)std::cout<< i<<' ';std::cout<<'\n'; // copy the rotation result directly to the std::cout    pivot=std::find(dest.begin(), dest.end(),1);    std::rotate_copy(dest.begin(), pivot, dest.end(),std::ostream_iterator<int>(std::cout," "));std::cout<<'\n';}

      Output:

      3 4 5 1 21 2 3 4 5

      [edit]See also

      rotates the order of elements in a range
      (function template)[edit]
      copies and rotate a range of elements
      (algorithm function object)[edit]
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/algorithm/rotate_copy&oldid=181154"

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