Creating an Array of References

Creating an array of references in C++ is not directly possible. This is because references must be initialized when they are created and cannot be reseated (made to refer to a different object) later. However, there are a few workarounds that can achieve similar functionality.

Using std::reference_wrapper

The most common and recommended approach is to use std::reference_wrapper from the <functional> header. This class template wraps a reference in a copyable, assignable object:

1#include <array>
2#include <functional>
3#include <iostream>
4
5int main() {
6  int a{1}, b{2}, c{3};
7
8  std::array<
9    std::reference_wrapper<int>, 3
10  > refArray{a, b, c};
11
12  for (auto& ref : refArray) {
13    std::cout << ref << ' ';
14    ref.get()++;  // Modify the original values
15  }
16  std::cout << '\n';
17
18  std::cout << "a: " << a
19    << ", b: " << b
20    << ", c: " << c << '\n';
21}

11 2 3
2a: 2, b: 3, c: 4

In this example, we create an array of std::reference_wrapper<int>. We can access and modify the original values through this array.

Using Pointers

Another approach is to use an array of pointers. While not exactly the same as references, pointers can achieve similar functionality:

1#include <array>
2#include <iostream>
3
4int main() {
5  int a{1}, b{2}, c{3};
6
7  std::array<int*, 3> ptrArray{&a, &b, &c};
8
9  for (auto ptr : ptrArray) {
10    std::cout << *ptr << ' ';
11    (*ptr)++;
12  }
13  std::cout << '\n';
14
15  std::cout << "a: " << a
16    << ", b: " << b
17    << ", c: " << c << '\n';
18}

11 2 3
2a: 2, b: 3, c: 4

This approach uses pointers instead of references, but achieves a similar result.

Remember, while these methods allow you to create collections of references or reference-like objects, they each have their own implications for syntax and semantics. The std::reference_wrapper approach is generally preferred as it more closely mimics the behavior of actual references.