View source for cpp/iterator/sentinel for

You do not have permission to edit this page, for the following reason:

Due to recent vandalism, editing of this page is temporarily disabled for new users.If you want to suggest a change, please leave a message on the suggestions page for new users instead (don't be surprised if that page appears vandalized!).

You can view and copy the source of this page:

{{cpp/title|sentinel_for}}
{{cpp/iterator/navbar}}
{{ddcl|header=iterator|since=c++20|1=
template< class S, class I >
    concept sentinel_for =
        std::semiregular<S> &&
        std::input_or_output_iterator<I> &&
        __WeaklyEqualityComparableWith<S, I>;
}}

The {{tt|sentinel_for}} concept specifies the relationship between an {{lconcept|input_or_output_iterator}} type and a {{lconcept|semiregular}} type whose values denote a range. The exposition-only concept {{tt|''__WeaklyEqualityComparableWith''}} is described in {{lconcept|equality_comparable}}.

===Semantic requirements===
Let {{tt|s}} and {{tt|i}} be values of type {{tt|S}} and {{tt|I}}, respectively, such that {{range|i|s}} denotes a [[cpp/iterator#Ranges|range]]. {{tt|sentinel_for&lt;S, I>}} is modeled only if:

* {{c|1=i == s}} is well-defined.
* If {{c|1=bool(i != s)}} then {{tt|i}} is dereferenceable and {{range|++i|s}} denotes a range.
* {{c|std::assignable_from<I&, S>}} is either modeled or not satisfied.

The domain of {{tt|1===}} can change over time. Given an iterator {{tt|i}} and sentinel {{tt|s}} such that {{range|i|s}} denotes a range and {{c|1=i != s}}, {{range|i|s}} is not required to continue to denote a range after incrementing any iterator equal to {{tt|i}} (and so {{c|1=i == s}} is no longer required to be well-defined after such an increment).

===Notes===
A sentinel type and its corresponding iterator type are not required to model {{lconcept|equality_comparable_with}}, because the sentinel type may not be comparable with itself, and they are not required to have a common reference type.

It has been permitted to use a sentinel type different from the iterator type in the [[cpp/language/range-for|range-based {{tt|for}} loop]] since C++17.

===Defect reports===
{{dr list begin}}
{{dr list item|wg=lwg|dr=3453|std=C++20|before=semantic requirements for {{tt|sentinel_for}} were too loose for {{tt|ranges::advance}}|after=strengthened}}
{{dr list end}}

{{langlinks|es|ja|zh}}

Templates used on this page:

Template:! (view source) (protected)
Template:box/core (edit)
Template:c (view source) (protected)
Template:c/core (view source) (protected)
Template:cpp/iterator/navbar (edit)
Template:cpp/iterator/navbar content (edit)
Template:cpp/iterator/navbar heading (edit)
Template:cpp/navbar content (edit)
Template:cpp/navbar heading (edit)
Template:cpp/title (view source) (protected)
Template:ctitle (view source) (protected)
Template:dcl (view source) (protected)
Template:dcl begin (view source) (protected)
Template:dcl end (view source) (protected)
Template:dcl header (view source) (protected)
Template:dcl list header/link (edit)
Template:dcl sep (view source) (protected)
Template:dcl/std (view source) (semi-protected)
Template:ddcl (view source) (protected)
Template:dr list begin (edit)
Template:dr list end (edit)
Template:dr list item (edit)
Template:dsc header/link (edit)
Template:get lang (view source) (protected)
Template:get lang formal (edit)
Template:langlinks (view source) (protected)
Template:langlinks/one (view source) (protected)
Template:lconcept (edit)
Template:lconcept/cat (edit)
Template:lconcept/pg (edit)
Template:lconcept/title (edit)
Template:lines (view source) (protected)
Template:ls (edit)
Template:ltt/core (view source) (protected)
Template:mark c++11 (view source) (protected)
Template:mark c++14 (view source) (protected)
Template:mark c++17 (view source) (protected)
Template:mark c++20 (edit)
Template:mark c++23 (view source) (protected)
Template:mark c++26 (

cppreference.com

Namespaces

Variants

Views

Actions

View source for cpp/iterator/sentinel for