Copying between Custom Containers

Using std::ranges::copy() with custom containers that do not support iterators is not directly possible because the ranges library relies on iterators to traverse the elements of the container.

However, you can make your custom container compatible with the ranges library by implementing the necessary iterator support.

To make your custom container work with std::ranges::copy(), you need to provide begin() and end() methods that return iterators.

Here’s an example of a simple custom container with iterator support:

1#include <algorithm>
2#include <iostream>
3#include <ranges>
4#include <vector>
5
6// Custom container class
7class CustomContainer {
8 public:
9  CustomContainer(std::initializer_list<int> list)
10    : data(list) {}
11
12  // Use vector's iterator types directly
13  using iterator
14    = std::vector<int>::iterator;
15  using const_iterator
16    = std::vector<int>::const_iterator;
17
18  iterator begin() { return data.begin(); }
19  iterator end() { return data.end(); }
20
21  const_iterator begin() const {
22    return data.begin(); }
23  const_iterator end() const {
24    return data.end(); }
25
26 private:
27  std::vector<int> data;
28};
29
30int main() {
31  CustomContainer Source{1, 2, 3, 4, 5};
32  std::vector<int> Destination(5);
33
34  std::ranges::copy(Source, Destination.begin());
35
36  for (int Value : Destination) {
37    std::cout << Value << ", ";
38  }
39}

11, 2, 3, 4, 5,

In this example, we define a CustomContainer class that holds data in a std::vector<int>.

We also define an Iterator class and implement the necessary iterator operations (operator*, operator++, and operator!=). The begin() and end() methods return iterators to the start and end of the container.

By implementing iterator support in your custom container, you can use it with std::ranges::copy() and other ranges algorithms.

This approach allows you to leverage the power of the C++ ranges library with your own data structures.