tmp/tmpdgfvwbf0/{from.md → to.md}
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#### Class `unreachable_sentinel_t` <a id="unreachable.sentinel">[[unreachable.sentinel]]</a>
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Class `unreachable_sentinel_t` can be used with any
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`weakly_incrementable` type to denote the “upper bound” of an unbounded
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interval.
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[*Example 1*:
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``` cpp
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char* p;
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// set p to point to a character buffer containing newlines
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char* nl = find(p, unreachable_sentinel, '\n');
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```
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Provided a newline character really exists in the buffer, the use of
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`unreachable_sentinel` above potentially makes the call to `find` more
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efficient since the loop test against the sentinel does not require a
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conditional branch.
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— *end example*]
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``` cpp
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namespace std {
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struct unreachable_sentinel_t {
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template<weakly_incrementable I>
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friend constexpr bool operator==(unreachable_sentinel_t, const I&) noexcept
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{ return false; }
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};
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}
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```
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