Standard library header <initializer_list>

namespace std {
  template<class E> class initializer_list {
  public:
    using value_type = E;
    using reference = const E&;
    using const_reference = const E&;
    using size_type = size_t;
    using iterator = const E*;
    using const_iterator = const E*;
    constexpr initializer_list() noexcept;
    constexpr size_t size() const noexcept; // number of elements
    constexpr const E* begin() const noexcept; // first element
    constexpr const E* end() const noexcept; // one past the last element
  };
  // initializer list range access
  template<class E> constexpr const E* begin(initializer_list<E> il) noexcept;
  template<class E> constexpr const E* end(initializer_list<E> il) noexcept;
}