std::ranges::sized_range, std::ranges::disable_sized_range - cppreference.com (original) (raw)
| Defined in header | ||
|---|---|---|
| (1) | ||
| template< class T > concept sized_range = ranges::range<T> && requires(T& t) { ranges::size(t); }; | (since C++20) (until C++26) | |
| template< class T > concept sized_range = ranges::approximately_sized_range<T> && requires(T& t) { ranges::size(t); }; | (since C++26) | |
| template< class > constexpr bool disable_sized_range = false; | (2) | (since C++20) |
The
sized_rangeconcept specifies the requirements of a range(until C++26)approximately_sized_range(since C++26) type that knows its size in constant time with thesizefunction.The
disable_sized_rangeexists to allow use of range types that provide asizefunction (either as a member or as a non-member) but do not in fact modelsized_range. Users may specializedisable_sized_rangefor cv-unqualified program-defined types. Such specializations shall be usable in constant expressions and have type const bool.
[edit] Semantic requirements
[edit] Notes
disable_sized_range cannot be used to opt-out a range whose iterator and sentinel satisfy sized_sentinel_for; std::disable_sized_sentinel_for must be used instead.
disable_sized_range cannot be specialized for array types or reference types.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
| __cpp_lib_ranges_reserve_hint | 202502L | (C++26) | ranges::approximately_sized_range and ranges::reserve_hint |
[edit] Example
#include #include #include static_assert ( std::ranges::sized_range<std::list> and not std::ranges::sized_range<std::forward_list> ); int main() {}