std::ranges::views::iota, std::ranges::iota_view

 

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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)

Views
view_interface	subrange

Range factories
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

 

std::ranges::iota_view

Member functions

iota_view::iota_view

iota_view::begin

iota_view::end

iota_view::empty

iota_view::size

Deduction guides

Nested classes

Iterator

Helper concepts

decrementable

advanceable

Member types

Member functions

iota_view::iterator::iterator

iota_view::iterator::operator*

iota_view::iterator::operator[]

iota_view::iterator::operator++ iota_view::iterator::operator++(int)

iota_view::iterator::operator-- iota_view::iterator::operator--(int)

iota_view::iterator::operator+=

iota_view::iterator::operator-=

Non-member functions

operator==(iota_view::iterator) operator<(iota_view::iterator) operator>(iota_view::iterator) operator<=(iota_view::iterator) operator>=(iota_view::iterator) operator<=>(iota_view::iterator)

operator+(iota_view::iterator)

operator-(iota_view::iterator)

Sentinel

Member functions

iota_view::sentinel::sentinel

Non-member functions

operator==(iota_view::iterator,iota_view::sentinel)

operator-(iota_view::iterator,iota_view::sentinel)

 

Defined in header <ranges>
template<std::weakly_incrementable W,           std::semiregular Bound =std::unreachable_sentinel_t>     requires /*weakly-equality-comparable-with*/<W, Bound>&&std::copyable<W> class iota_view     :publicranges::view_interface<iota_view<W, Bound>>	(1)	(since C++20)
namespace views {     inlineconstexpr/* unspecified */ iota =/* unspecified */; }	(2)	(since C++20)
Call signature
template<class W >     requires /* see below */ constexpr/* see below */ iota( W&& value );		(since C++20)
template<class W, class Bound >     requires /* see below */ constexpr/* see below */ iota( W&& value, Bound&& bound );		(since C++20)

1) A range factory that generates a sequence of elements by repeatedly incrementing an initial value. Can be either bounded or unbounded (infinite).

2)views::iota(e) and views::iota(e, f) are expression-equivalent to iota_view<std::decay_t<decltype((e))>>(e) and iota_view(e, f) respectively for any suitable subexpressions e and f.

Customization point objects

The name views::iota denotes a customization point object, which is a const function object of a literalsemiregular class type. See CustomizationPointObject for details.

Data members

Member	Definition
Wvalue_	the beginning value (exposition-only member object*)
Boundbound_	the sentinel value, may be unreachable (exposition-only member object*)

Member functions

(constructor)	creates an iota_view (public member function)
begin	obtains the beginning iterator of an iota_view (public member function)
end	obtains the sentinel denoting the end of an iota_view (public member function)
empty	tests whether the iota_view is empty (i.e. the iterator and the sentinel compare equal) (public member function)
size (optional)	obtains the size of an iota_view (only provided if it is bounded) (public member function)
Inherited from std::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>)
cend (C++23)	returns a sentinel for the constant iterator of the range (public member function of std::ranges::view_interface<D>)
operator bool	returns whether the derived view is not empty, provided only if ranges::empty is applicable to it (public member function of std::ranges::view_interface<D>)
front	returns the first element in the derived view, provided if it satisfies forward_range (public member function of std::ranges::view_interface<D>)
back	returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range (public member function of std::ranges::view_interface<D>)
operator[]	returns the nth element in the derived view, provided only if it satisfies random_access_range (public member function of std::ranges::view_interface<D>)

Nested classes

iterator	the iterator type (exposition-only member class*)
sentinel	the sentinel type used when the iota_view is bounded and Bound and W are not the same type (exposition-only member class*)

Helper templates

template<std::weakly_incrementable W, std::semiregular Bound > constexprboolranges::enable_borrowed_range<ranges::iota_view<W, Bound>>=true;		(since C++20)

This specialization of ranges::enable_borrowed_range makes iota_view satisfy borrowed_range.

Example

Run this code

#include <algorithm>#include <iostream>#include <ranges>   struct Bound {int bound;bool operator==(int x)const{return x == bound;}};   int main(){for(int i : std::ranges::iota_view{1, 10})std::cout<< i <<' ';std::cout<<'\n';   for(int i : std::views::iota(1, 10))std::cout<< i <<' ';std::cout<<'\n';   for(int i : std::views::iota(1, Bound{10}))std::cout<< i <<' ';std::cout<<'\n';   for(int i : std::views::iota(1)| std::views::take(9))std::cout<< i <<' ';std::cout<<'\n';   std::ranges::for_each(std::views::iota(1, 10), [](int i){std::cout<< i <<' ';});std::cout<<'\n';}

Output:

1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9

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 4096	C++20	views::iota could copy an iota_view as-is	forbidden
P2325R3	C++20	iota_view required that W is semiregular as view required default_initializable	only requires that W is copyable

See also

iota (C++11)	fills a range with successive increments of the starting value (function template)
ranges::iota (C++23)	fills a range with successive increments of the starting value (algorithm function object)
ranges::repeat_viewviews::repeat (C++23)	a view consisting of a generated sequence by repeatedly producing the same value (class template)(customization point object)
ranges::enumerate_viewviews::enumerate (C++23)	a view that maps each element of adapted sequence to a tuple of both the element's position and its value (class template)(range adaptor object)