std::ranges::sized_range,std::ranges::disable_sized_range

From cppreference.com

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros(C++20)
Language support library
Concepts library(C++20)
Diagnostics library
Memory management library
Metaprogramming library(C++11)
General utilities library
Containers library
Iterators library
Ranges library(C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library(C++17)
Concurrency support library(C++11)
Execution control library(C++26)
Technical specifications
Symbols index
External libraries

[edit]

Ranges library

Range access

begin
cbegin
end
cend

rbegin
crbegin
rend
crend

size
ssize
data
cdata

reserve_hint (C++26)
empty

Range conversions
std::from_range_t std::from_range (C++23)(C++23)
to (C++23)

Dangling iterator handling
dangling
borrowed_iterator_t
borrowed_subrange_t

Range primitives

range_size_trange_difference_trange_value_t
elements_of (C++23)

iterator_tconst_iterator_tsentinel_tconst_sentinel_t

(C++23)(C++23)

range_reference_trange_const_reference_trange_rvalue_reference_trange_common_reference_t

(C++23)

Range concepts

range
borrowed_range
common_range

sized_range
viewable_range
view

input_range
output_range
forward_range

bidirectional_range
random_access_range
contiguous_range

approximately_sized_range (C++26)
constant_range (C++23)

empty_viewviews::empty

single_viewviews::single

basic_istream_viewviews::istream

iota_viewviews::iota

repeat_viewviews::repeat

(C++23)(C++23)

Range adaptors

views::all_tviews::all
as_rvalue_viewviews::as_rvalue (C++23)(C++23)
filter_viewviews::filter
transform_viewviews::transform
take_viewviews::take
take_while_viewviews::take_while
common_viewviews::common
views::counted
to_input_viewviews::to_input (C++26)(C++26)

ref_view
drop_viewviews::drop
drop_while_viewviews::drop_while
lazy_split_viewviews::lazy_split
split_viewviews::split
join_viewviews::join
join_with_viewviews::join_with (C++23)(C++23)
concat_viewviews::concat (C++26)(C++26)
cache_latest_viewviews::cache_latest (C++26)(C++26)

owning_view
reverse_viewviews::reverse
as_const_viewviews::as_const (C++23)(C++23)
elements_viewviews::elements
keys_viewviews::keys
values_viewviews::values
enumerate_viewviews::enumerate (C++23)(C++23)
zip_viewviews::zip (C++23)(C++23)
zip_transform_viewviews::zip_transform (C++23)(C++23)

adjacent_viewviews::adjacent (C++23)(C++23)
views::pairwise (C++23)
adjacent_transform_viewviews::adjacent_transform (C++23)(C++23)
views::pairwise_transform (C++23)
chunk_viewviews::chunk (C++23)(C++23)
slide_viewviews::slide (C++23)(C++23)
chunk_by_viewviews::chunk_by (C++23)(C++23)
stride_viewviews::stride (C++23)(C++23)
cartesian_product_viewviews::cartesian_product (C++23)(C++23)

Range generators
std::generator (C++23)

Range adaptor closure objects
range_adaptor_closure (C++23)

Range adaptor objects

Helper items

copyable-box
movable-box

(until C++23) (C++23)

simple-view
non-propagating-cache

[edit]

Defined in header`<ranges>`
	(1)
template<class T> concept sized_range=ranges::range<T>&& requires(T& t){ ranges::size(t); };			(since C++20) (until C++26)
template<class T> concept sized_range= ranges::approximately_sized_range<T>&& requires(T& t){ ranges::size(t); };			(since C++26)
template<class> constexprbool disable_sized_range=false;		(2)	(since C++20)

1) Thesized_range concept specifies the requirements of arange(until C++26)approximately_sized_range(since C++26) type that knows its size in constant time with thesize function.

2) Thedisable_sized_range exists to allow use of range types that provide asize function (either as a member or as a non-member) but do not in fact modelsized_range. Users may specializedisable_sized_range for cv-unqualified program-defined types. Such specializations shall be usable inconstant expressions and have typeconstbool.

[edit]Semantic requirements

1) Given an lvaluet of typestd::remove_reference_t<T>,T modelssized_range only if

ranges::size(t)

has amortized constant-time complexity,
does not alter the value oft in a manner observable toequality-preserving expressions, and
is equal toranges::distance(ranges::begin(t),ranges::end(t)), and

ifranges::iterator_t<T> modelsforward_iterator,ranges::size(t) is well-defined regardless of the evaluation ofranges::begin(t) (in other words, a single-pass sized range may support a call to size only before the first call to begin, but a forward range must support size at all times).

[edit]Notes

disable_sized_range cannot be used to opt-out a range whose iterator and sentinel satisfysized_sentinel_for;std::disable_sized_sentinel_for must be used instead.

disable_sized_range cannot be specialized for array types or reference types.

Feature-test macro	Value	Std	Feature
`__cpp_lib_ranges_reserve_hint`	`202502L`	(C++26)	ranges::approximately_sized_range andranges::reserve_hint

[edit]Example

Run this code

#include <forward_list>#include <list>#include <ranges> static_assert(    std::ranges::sized_range<std::list<int>> and    not std::ranges::sized_range<std::forward_list<int>>); int main(){}

[edit]See also

ranges::random_access_range (C++20)	specifies a range whose iterator type satisfies`random_access_iterator` (concept)[edit]
ranges::contiguous_range (C++20)	specifies a range whose iterator type satisfies`contiguous_iterator` (concept)[edit]

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/ranges/sized_range&oldid=182365"

Movatterモバイル変換

cppreference.com

Namespaces

Variants

Views

Actions

std::ranges::sized_range,std::ranges::disable_sized_range

Contents

[edit]Semantic requirements

[edit]Notes

[edit]Example

[edit]See also

Navigation

Toolbox