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

 

C++

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Freestanding and hosted

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Feature test macros (C++20)

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Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

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Numerics library

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Filesystem library (C++17)

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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 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    sized_range	common_range view viewable_range	input_range output_range forward_range	bidirectional_range    random_access_range contiguous_range	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 ref_view owning_view as_rvalue_viewviews::as_rvalue (C++23)(C++23)   filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while concat_viewviews::concat (C++26)(C++26)	drop_viewviews::drop drop_while_viewviews::drop_while join_viewviews::join join_with_viewviews::join_with (C++23)(C++23)   lazy_split_viewviews::lazy_split split_viewviews::split views::counted common_viewviews::common	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::subrange

Member functions

subrange::subrange

subrange::operator PairLike

Observers

subrange::begin

subrange::end

subrange::empty

subrange::size

Iterator operations

subrange::advance

subrange::next

subrange::prev

Deduction guides

Non-member functions

get(std::ranges::subrange)

Helper types

subrange_kind

tuple_size<std::ranges::subrange>

tuple_element<std::ranges::subrange>

 

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

Increments or decrements begin_ :

• If I models bidirectional_iterator and n < 0 is true, decrements begin_ by -n elements. Equivalent to:

ranges::advance(begin_ , n);
if constexpr (StoreSize )
    size_ += to-unsigned-like (-n);
return *this;.

• Otherwise, increments begin_ by n elements, or until end_ is reached. Equivalent to:

auto d = n - ranges::advance(begin_ , n, end_ );
if constexpr (StoreSize )
    size_ -= to-unsigned-like (d);
return *this;.

According to the preconditions of ranges::advance, if n < 0 is true and begin_ cannot be decremented by -n elements, the behavior is undefined.

Parameters

n

-

number of maximal increments of the iterator

Return value

*this

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 behavior was undefined if n < 0	made well-defined if begin_ can be decremented

See also

next	obtains a copy of the subrange with its iterator advanced by a given distance (public member function)
prev	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)