std::ranges::drop_view<V>::begin

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General 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)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
Range conversions
to (C++23)
Range primitives
range_size_trange_difference_t range_value_t	range_reference_trange_const_reference_trange_rvalue_reference_t   (C++23)	iterator_tconst_iterator_tsentinel_t (C++23)
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range    sized_range constant_range (C++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Factories
empty_viewviews::empty iota_viewviews::iota	single_viewviews::single basic_istream_viewviews::istream	repeat_viewviews::repeat (C++23)(C++23)
Adaptors
ref_view views::all_tviews::all common_viewviews::common owning_view views::counted reverse_viewviews::reverse zip_viewviews::zip (C++23)(C++23) as_const_viewviews::as_const (C++23)(C++23) as_rvalue_viewviews::as_rvalue (C++23)(C++23)	take_viewviews::take take_while_viewviews::take_while drop_viewviews::drop drop_while_viewviews::drop_while zip_transform_viewviews::zip_transform (C++23)(C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23)   cartesian_product_viewviews::cartesian_product (C++23)(C++23)	elements_viewviews::elements keys_viewviews::keys values_viewviews::values transform_viewviews::transform adjacent_viewviews::adjacent (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) stride_viewviews::stride (C++23)(C++23)	filter_viewviews::filter join_viewviews::join split_viewviews::split lazy_split_viewviews::lazy_split join_with_viewviews::join_with (C++23)(C++23) chunk_viewviews::chunk (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23)
Range adaptor objects
Range adaptor closure objects
Helper items
copyable-box	simple-view

 

std::ranges::drop_view

Member functions

drop_view::drop_view (C++20)

drop_view::base (C++20)

drop_view::begin (C++20)

drop_view::end (C++20)

drop_view::size (C++20)

Deduction guides

 

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

Returns an iterator to the first element of the drop_view, that is, an iterator to the N-th element of the underlying view, or to the end of the underlying view if it has less than N elements.

If V is not a random_access_range or a sized_range, in order to provide the amortized constant time complexity required by the range concept, the overload (1) caches the result within the drop_view object for use on subsequent calls.

Parameters

(none)

Return value

ranges::next(ranges::begin(base_), count_, ranges::end(base_)), where base_ is the underlying view, and count_ is the number of elements to skip.

Example

Run this code

#include <algorithm>
#include <array>
#include <iostream>
#include <iterator>
#include <ranges>
 
int main()
{
    std::array hi{ 'H','e','l','l','o',',',' ','C','+','+','2','0','!' };
 
    std::ranges::for_each(hi, [](const char c){ std::cout << c; });
    std::cout << '\n';
 
    const auto c = std::distance(hi.begin(), std::ranges::find(hi, 'C'));
    auto cxx = std::ranges::drop_view{ hi, c };
    std::cout << "*drop_view::begin() == '" << *cxx.begin() << "'\n";
 
//  *cxx.begin() = 'c'; // undefined: 'views' are to be used as observers
 
    for (char c : cxx) { std::cout << c; }
    std::cout << '\n';
}

Output:

Hello, C++20!
*drop_view::begin() == 'C'
C++20!

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 3482	C++20	the const overload can be called with unsized ranges	the const overload requires sized_range

See also

end (C++20)	returns an iterator or a sentinel to the end (public member function)
ranges::begin (C++20)	returns an iterator to the beginning of a range (customization point object)
ranges::end (C++20)	returns a sentinel indicating the end of a range (customization point object)