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std::ranges::join_view<V>::begin - cppreference.com

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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 /*simple-view*/<V> is satisfied and ranges::range_reference_t<V> is reference type. Otherwise,
  • return /*iterator*/<false>{*this, ranges::begin(base_)};.

2) Equivalent to return /*iterator*/<true>{*this, ranges::begin(base_)};.

Parameters

(none)

Return value

Iterator to the first element.

Notes

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.

Example

See also

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