Difference between revisions of "cpp/iterator/weakly incrementable"
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===Integer-like types=== | ===Integer-like types=== | ||
| − | An | + | An integer-like type is an (possibly cv-qualified) integer type (except for ''cv'' {{c|bool}}) or a class that behaves like an integer type, including all operators, implicit conversions, and {{lc|std::numeric_limits}} specializations. If a integer-like type only represents non-negative values, it is unsigned-integer-like, otherwise it is signed-integer-like. |
===Defect reports=== | ===Defect reports=== | ||
Revision as of 10:21, 2 June 2021
| Defined in header <iterator>
|
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| template<class I> concept weakly_incrementable = |
(since C++20) | |
where /*is-signed-integer-like*/<I> is true if and only if I is a signed-integer-like type (see below).
This concept specifies requirements on types that can be incremented with the pre- and post-increment operators, but those increment operations are not necessarily equality-preserving, and the type itself is not required to be std::equality_comparable.
For std::weakly_incrementable types, a == b does not imply that ++a == ++b. Algorithms on weakly incrementable types must be single-pass algorithms. These algorithms can be used with istreams as the source of the input data through std::istream_iterator.
Contents |
Semantic requirements
I models std::weakly_incrementable only if given only object i of type I:
- The expressions ++i and i++ have the same domain
- If
iis incrementable, then both ++i and i++ advancei - If
iis incrementable, then std::addressof(++i) == std::addressof(i)
Integer-like types
An integer-like type is an (possibly cv-qualified) integer type (except for cv bool) or a class that behaves like an integer type, including all operators, implicit conversions, and std::numeric_limits specializations. If a integer-like type only represents non-negative values, it is unsigned-integer-like, otherwise it is signed-integer-like.
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 3467 | C++20 | bool was considered as an integer-like type | excluded |
See also
| (C++20) |
specifies that the increment operation on a weakly_incrementable type is equality-preserving and that the type is equality_comparable (concept) |
