std::ranges::subrange<I,S,K>::advance

 

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Ranges library

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begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
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to (C++23)
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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)
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dangling	borrowed_iterator_t	borrowed_subrange_t
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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
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empty_viewviews::empty iota_viewviews::iota	single_viewviews::single basic_istream_viewviews::istream	repeat_viewviews::repeat (C++23)(C++23)
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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)
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copyable-box	simple-view

 

std::ranges::subrange

Member functions

subrange::subrange (C++20)

subrange::operator PairLike (C++20)

Observers

subrange::begin (C++20)

subrange::end (C++20)

subrange::empty (C++20)

subrange::size (C++20)

Iterator operations

subrange::advance (C++20)

subrange::next (C++20)

subrange::prev (C++20)

Deduction guides

Non-member functions

get (C++20)

Helper types

subrange_kind (C++20)

tuple_size (C++20)

tuple_element (C++20)

 

constexpr subrange& advance( std::iter_difference_t<I> n );		(since C++20)

If n >= 0, increments the stored iterator for n times, or until it is equal to the stored sentinel, whichever comes first. Otherwise, decrements the stored iterator for -n times.

The stored size, if any, is adjusted accordingly (increased by -n if n < 0, decreased by m otherwise, where m is the number of increments actually applied to the iterator).

The behavior is undefined if

• I does not model bidirectional_iterator and n < 0, or
• the stored iterator is decremented after becoming a non-decrementable value.

Parameters

n

-

number of maximal increments of the iterator

Return value

*this

Complexity

Generally min(n, size()) increments or -n decrements on the iterator, when n >= 0 or n < 0 respectively.

Constant if I models random_access_iterator, and either n < 0 or std::sized_sentinel_for<S, I> is modeled.

Notes

The stored size presents if and only if K == ranges::subrange_kind::sized but std::sized_sentinel_for<S, I> is not satisfied.

Example

Run this code

#include <algorithm>
#include <array>
#include <iostream>
#include <iterator>
#include <ranges>
 
void print(auto name, auto const sub) {
    std::cout << name << ".size() == " << sub.size() << "; { ";
    std::ranges::for_each(sub, [](int x) { std::cout << x << ' '; });
    std::cout << "}\n";
};
 
int main()
{
    std::array arr{1,2,3,4,5,6,7};
    std::ranges::subrange sub{ std::next(arr.begin()), std::prev(arr.end()) };
    print("1) sub", sub);
    print("2) sub", sub.advance(3));
    print("3) sub", sub.advance(-2));
}

Output:

1) sub.size() == 5; { 2 3 4 5 6 }
2) sub.size() == 2; { 5 6 }
3) sub.size() == 4; { 3 4 5 6 }

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 3433	C++20	the specification mishandled the cases when n < 0	corrected

See also

next (C++20)	obtains a copy of the subrange with its iterator advanced by a given distance (public member function)
prev (C++20)	obtains a copy of the subrange with its iterator decremented by a given distance (public member function)
advance	advances an iterator by given distance (function template)
ranges::advance (C++20)	advances an iterator by given distance or to a given bound (niebloid)