std::indirect_array (3) Linux Manual Page

std::indirect_array – std::indirect_array

Synopsis

Defined in header <valarray>

template< class T > class indirect_array;

std::gslice_array is a helper template used by std::indirect_array subscript operator. It has reference semantics to a subset of the array specified by an indirect array (std::valarray<std::size_t> object).

Member types

Type Definition
value_type T

Member functions

              constructs a indirect_array
constructor (public member function)
              destroys a indirect_array
destructor (public member function)
              assigns contents
operator= (public member function)

operator+=
operator-=
operator*=
operator/= performs arithmetic operation on the array referred by indirect array.
operator%= (public member function)
operator&=
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 indexes '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