std::ranges::views::istream,std::ranges::basic_istream_view,std::ranges::istream_view,std::ranges::wistream_view

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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
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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]

std::ranges::basic_istream_view

Member functions
basic_istream_view::basic_istream_view
basic_istream_view::begin
basic_istream_view::end
Iterator
basic_istream_view::iterator::iterator
basic_istream_view::iterator::operator=
basic_istream_view::iterator::operator++
basic_istream_view::iterator::operator*
operator==(basic_istream_view::iterator)

[edit]

Defined in header`<ranges>`
template<std::movable Val,class CharT, class Traits=std::char_traits<CharT>> requiresstd::default_initializable<Val>&& /stream-extractable/<Val, CharT, Traits> class basic_istream_view :publicranges::view_interface<basic_istream_view<Val, CharT, Traits>>	(1)	(since C++20)
Helper templates
template<class Val> using istream_view= ranges::basic_istream_view<Val,char>;	(2)	(since C++20)
template<class Val> using wistream_view= ranges::basic_istream_view<Val,wchar_t>;	(3)	(since C++20)
Customization point objects
namespace views{ template<class T> constexpr/* unspecified / istream=/ unspecified */; }	(4)	(since C++20)
Helper concepts
template<class Val,class CharT,class Traits> concept/stream-extractable/= requires(std::basic_istream<CharT, Traits>& is, Val& t){ is>> t; };	(5)	(exposition only*)

1) A range factory that generates a sequence of elements by repeatedly callingoperator>>.

2,3) Convenience alias templates for character typeschar andwchar_t.

4)views::istream<T>(e) isexpression-equivalent toranges::basic_istream_view<T,typename U::char_type,typename U::traits_type>(e) for any suitable subexpressionse, whereU isstd::remove_reference_t<decltype(e)>.

The program is ill-formed ifU is not both publicly and unambiguously derived fromstd::basic_istream<typename U::char_type,typename U::traits_type>, which may result in asubstitution failure.

5) The exposition-only concept/*stream-extractable*/<Val, CharT, Traits> is satisfied when lvalue of typeVal can be extracted from lvalue of typestd::basic_istream<CharT, Traits>.

The iterator type ofbasic_istream_view is move-only: it does not meet theLegacyIterator requirements, and thus does not work with pre-C++20algorithms.

Customization point objects

The nameviews::istream<T> denotes acustomization point object, which is a constfunction object of aliteral semiregular class type. SeeCustomizationPointObject for details.

[edit]Data members

Member	Definition
std::basic_istream<CharT, Traits>*`stream_`	a pointer to the input stream (exposition-only member object*)
`Valvalue_`	the stored value (exposition-only member object*)

[edit]Member functions

(constructor)	constructs a`basic_istream_view` (public member function)
begin	returns an iterator (public member function)
end	returnsstd::default_sentinel (public member function)
Inherited fromstd::ranges::view_interface
cbegin (C++23)	returns a constant iterator to the beginning of the range (public member function of`std::ranges::view_interface<D>`)[edit]
cend (C++23)	returns a sentinel for the constant iterator of the range (public member function of`std::ranges::view_interface<D>`)[edit]

Althoughbasic_istream_view is derived fromstd::ranges::view_interface, it cannot use any of inherited member functions.

(until C++23)

std::ranges::basic_istream_view::basic_istream_view

constexprexplicit basic_istream_view(std::basic_istream<CharT, Traits>& stream);		(since C++20)

Initializesstream_ withstd::addressof(stream), and value-initializesvalue_ .

std::ranges::basic_istream_view::begin

constexprauto begin();		(since C++20)

Equivalent to*stream_ >> value_ ;return iterator {*this};.

std::ranges::basic_istream_view::end

constexprstd::default_sentinel_t end()constnoexcept;		(since C++20)

Returnsstd::default_sentinel.

[edit]Nested classes

iterator

the iterator type ofbasic_istream_view
(exposition-only member class*)

[edit]Example

Run this code

#include <algorithm>#include <iomanip>#include <iostream>#include <iterator>#include <ranges>#include <sstream>#include <string> int main(){auto words=std::istringstream{"today is yesterday’s tomorrow"};for(constauto& s: std::views::istream<std::string>(words))std::cout<<std::quoted(s,'/')<<' ';std::cout<<'\n'; auto floats=std::istringstream{"1.1  2.2\t3.3\v4.4\f55\n66\r7.7  8.8"};    std::ranges::copy(        std::views::istream<float>(floats),std::ostream_iterator<float>{std::cout,", "});std::cout<<'\n';}

Output:

/today/ /is/ /yesterday’s/ /tomorrow/1.1, 2.2, 3.3, 4.4, 55, 66, 7.7, 8.8,

[edit]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 3568	C++20	P2325R3 accidentally made the stored value default-initialized	restored to value-initialization
P2325R3	C++20	default constructor was provided as `view` must be`default_initializable`	removed along with the requirement
P2432R1	C++20	`ranges::istream_view` was a function template and did not follow the naming convention	made an alias template; customization point objects added