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      std::indirect_array

      From cppreference.com
      <cpp‎ |numeric‎ |valarray
       
       
       
      std::valarray
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      Defined in header<valarray>
      template<class T>class indirect_array;

      std::indirect_array is a helper template used by thevalarray subscript operator withstd::valarray<std::size_t> argument. It has reference semantics to a subset of the array whose indices specified by thestd::valarray<std::size_t> object.

      [edit]Member types

      Type Definition
      value_typeT

      [edit]Member functions

      constructs aindirect_array
      (public member function)[edit]
      destroys aindirect_array
      (public member function)[edit]
      assigns contents
      (public member function)[edit]
      performs arithmetic operation on the array referred by indirect array.
      (public member function)[edit]

      [edit]Example

      Run this code
      #include <iostream>#include <valarray> int main(){std::valarray<int> data{0,1,2,3,4,5,6,7,8,9}; std::valarray<std::size_t> idx{0,2,4,6,8}; std::cout<<"Original valarray: ";for(int n: data)std::cout<< n<<' ';std::cout<<'\n';     data[idx]+= data[idx];// double the values at indices 'idx' // the type of data[idx] is std::indirect_array<int> std::cout<<"After indirect modification: ";for(int n: data)std::cout<< n<<' ';std::cout<<'\n';}

      Output:

      Original valarray: 0 1 2 3 4 5 6 7 8 9 After indirect modification: 0 1 4 3 8 5 12 7 16 9
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/numeric/valarray/indirect_array&oldid=170727"

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