std::ranges::take_view<V>::begin

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
Range primitives
iterator_tsentinel_t	range_size_trange_difference_t	range_value_t	range_reference_trange_rvalue_reference_t
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range sized_range	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Semiregular wrapper
Factories
empty_viewviews::empty	single_viewviews::single	iota_viewviews::iota	views::counted
Adaptors
views::all_tviews::all join_viewviews::join take_viewviews::take basic_istream_viewistream_view	ref_view                                split_viewviews::split take_while_viewviews::take_while elements_viewviews::elements	common_viewviews::common transform_viewviews::transform drop_viewviews::drop keys_viewviews::keys	reverse_viewviews::reverse filter_viewviews::filter drop_while_viewviews::drop_while values_viewviews::values

 

std::ranges::take_view

Member functions

take_view::take_view

take_view::base

take_view::begin

take_view::end

take_view::size

Deduction guides

Sentinel

take_view::sentinel::sentinel

take_view::sentinel::base

operator==(std::counted_iterator,take_view::sentinel)

 

constexpr auto begin() requires (!__SimpleView<V>);	(1)	(since C++20)
constexpr auto begin() const requires ranges::range<const V>;	(2)	(since C++20)

Returns an iterator to the first element of the take_view.

1) Returns a std::counted_iterator or a ranges::range_iterator_t<V>.

2) Returns a std::counted_iterator or a ranges::range_iterator_t<const V>.

Overload (1) does not participate in overload resolution if V is a simple view (that is, if V and const V are views with the same iterator and sentinel types).

Parameters

(none)

Return value

The result depends on the concepts satisfied by V (for overload (1)) or const V (for overload (2)).

Let base_ be the underlying view, count_ be the number passed to the constructor (​0​ if default initialized), sz be the value of size().

The underlying view satisfies ...		random_access_range
		yes	no
sized_range	yes	ranges::begin(base_)	std::counted_iterator{ranges::begin(base_), sz}
	no	std::counted_iterator{ranges::begin(base_), count_}

Example

Run this code

#include <ranges>
#include <iostream>
#include <string_view>
using namespace std::literals;
 
int main()
{
    static constexpr auto sv = {"∀x"sv, "∃y"sv, "ε"sv, "δ"sv};
 
    std::cout << *std::ranges::take_view(sv, 8).begin() << '\n';
}

Output:

∀x

See also

end	returns an iterator or a sentinel to the end (public member function)
counted_iterator (C++20)	iterator adaptor that tracks the distance to the end of the range (class template)
operator==	compares a sentinel with an iterator returned from take_view::begin (function)