std::unreachable_sentinel_t, std::unreachable_sentinel - cppreference.com (original) (raw)
| Defined in header | ||
|---|---|---|
| struct unreachable_sentinel_t; | (1) | (since C++20) |
| inline constexpr unreachable_sentinel_t unreachable_sentinel{}; | (2) | (since C++20) |
unreachable_sentinel_tis an empty class type that can be used to denote the “upper bound” of an unbounded interval.unreachable_sentinelis a constant of typeunreachable_sentinel_t.
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[edit] Non-member functions
| | compares an unreachable_sentinel_t with a value of any weakly_incrementable type (function template) | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
operator==(std::unreachable_sentinel_t)
| template< std::weakly_incrementable I > friend constexpr bool operator==( unreachable_sentinel_t, const I& ) noexcept { return false; } | | (since C++20) | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ------------- |
unreachable_sentinel_t can be compared with any weakly_incrementable type and the result is always false.
This function template is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::unreachable_sentinel_t is an associated class of the arguments.