Modifying Containers through std::ranges::subrange

Yes, std::ranges::subrange can be used with standard library algorithms that modify the container.

Since std::ranges::subrange provides non-owning views of containers, you can apply algorithms to modify the elements within the subrange, and these changes will reflect in the original container.

Example with std::ranges::sort()

You can use std::ranges::sort() to sort elements within a subrange, and the changes will be reflected in the underlying container.

1#include <algorithm>
2#include <iostream>
3#include <ranges>
4#include <vector>
5
6int main() {
7  std::vector<int> Nums{5, 3, 4, 1, 2};
8  std::ranges::subrange view{
9    Nums.begin() + 1, Nums.end() - 1};
10
11  std::ranges::sort(view);  
12
13  for (int n : Nums) {
14    std::cout << n << ", ";
15  }
16}

15, 1, 3, 4, 2,

Example with std::ranges::reverse()

You can also use std::ranges::reverse() to reverse the elements within a subrange.

1#include <algorithm>
2#include <iostream>
3#include <ranges>
4#include <vector>
5
6int main() {
7  std::vector<int> Nums{1, 2, 3, 4, 5};
8  std::ranges::subrange view{
9    Nums.begin() + 1, Nums.end() - 1};
10
11  std::ranges::reverse(view);  
12
13  for (int n : Nums) {
14    std::cout << n << ", ";
15  }
16}

11, 4, 3, 2, 5,

Using std::ranges::for_each()

With std::ranges::for_each(), you can apply a custom function to each element in the subrange, modifying the elements in place.

1#include <algorithm>
2#include <iostream>
3#include <ranges>
4#include <vector>
5
6void increment(int& n) { n += 1; }  
7
8int main() {
9  std::vector<int> Nums{1, 2, 3, 4, 5};
10  std::ranges::subrange view{
11    Nums.begin(), Nums.end()};
12
13  std::ranges::for_each(view, increment);  
14
15  for (int n : Nums) {
16    std::cout << n << ", ";
17  }
18}

12, 3, 4, 5, 6,

Considerations

• Synchronization: Ensure proper synchronization when accessing or modifying the container in multi-threaded contexts.
• Iterator Validity: Be aware of algorithms that may invalidate iterators, which could lead to undefined behavior if the subrange iterators are used afterward.
• Non-Contiguous Ranges: Algorithms that require contiguous memory blocks may not work with subranges created from non-contiguous iterators.

Summary

std::ranges::subrange works seamlessly with standard library algorithms that modify the container.

By using subranges, you can apply various algorithms to a subset of the container while keeping the changes synchronized with the underlying data.