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std::indirect_array(3)	       C++ Standard Libary	  std::indirect_array(3)

NAME
     std::indirect_array - std::indirect_array

Synopsis
	Defined in header <valarray>
	template< class T > class indirect_array;

	std::indirect_array  is a helper template used by the valarray subscript
     operator
	with std::valarray<std::size_t> argument. It has reference semantics  to
     a subset of
	the  array whose indices specified by the std::valarray<std::size_t> ob-
     ject.

Member types
	Type	   Definition
	value_type T

Member functions
	constructor   constructs a indirect_array
		      (public member function)
	destructor    destroys a indirect_array
		      (public member function)
	operator=     assigns contents
		      (public member function)
	operator+=
	operator-=
	operator*=
	operator/=
	operator%=    performs arithmetic operation on the array referred by in-
     direct array.
	operator&=    (public member function)
	operator|=
	operator^=
	operator<<=
	operator>>=

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

http://cppreference.com 	   2024.06.10		  std::indirect_array(3)
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