18 Language support library [language.support]

The header <initializer_list> defines a class template and several support functions related to list-initialization (see [dcl.init.list]).

Header <initializer_list> synopsis

namespace std {
  template<class E> class initializer_list {
  public:
    typedef E value_type;
    typedef const E& reference;
    typedef const E& const_reference;
    typedef size_t size_type;

    typedef const E* iterator;
    typedef const E* const_iterator;

    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
  };

  // [support.initlist.range] 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;
}

An object of type initializer_list<E> provides access to an array of objects of type const E. [ Note: A pair of pointers or a pointer plus a length would be obvious representations for initializer_list. initializer_list is used to implement initializer lists as specified in [dcl.init.list]. Copying an initializer list does not copy the underlying elements.  — end note ]