std::indirect_array

< cpp‎ | numeric‎ | valarray
 
C++
 
Numerics library
 
std::valarray
Member functions
Non-member functions
Helper classes
indirect_array
Deduction guides(C++17)
 
std::indirect_array
 
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
(public member function)
destroys a indirect_array
(public member function)
assigns contents
(public member function)
performs arithmetic operation on the array referred by indirect array.
(public member function)

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