constexpr auto begin();
(1) (since C++20)
constexpr auto begin() const
    requires ranges::input_range<const V> &&
             std::is_reference_v<ranges::range_reference_t<const V>>;
(2) (since C++20)

Returns an iterator to the first element of the join_view. Given base_ is the underlying view,

1) Equivalent to return /*iterator*/<true>{*this, ranges::begin(base_)}; if __SimpleView<V> is satisfied and ranges::range_reference_t<V> is reference type. Otherwise, equivalent to return /*iterator*/<false>{*this, ranges::begin(base_)};.
2) Equivalent to return /*iterator*/<true>{*this, ranges::begin(base_)};.



Return value

Iterator to the first element.


When ranges::range_reference_t<V> is not a reference type, that is, deferencing an iterator of V returns a prvalue temporary, the join_view is only an input_range, in which case only single-pass iteration is supported, and repeated calls to begin() may not give meaningful results.


See also

returns an iterator or a sentinel to the end
(public member function)
returns an iterator to the beginning of a range
(customization point object)

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.