25 Algorithms library [algorithms]

25.8 Sorting and related operations [alg.sorting]

25.8.4 Binary search [alg.binary.search]

25.8.4.2 lower_­bound [lower.bound]

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template<class ForwardIterator, class T> constexpr ForwardIterator lower_bound(ForwardIterator first, ForwardIterator last, const T& value); template<class ForwardIterator, class T, class Compare> constexpr ForwardIterator lower_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp); template<forward_­iterator I, sentinel_­for<I> S, class T, class Proj = identity, indirect_­strict_­weak_­order<const T*, projected<I, Proj>> Comp = ranges::less> constexpr I ranges::lower_bound(I first, S last, const T& value, Comp comp = {}, Proj proj = {}); template<forward_­range R, class T, class Proj = identity, indirect_­strict_­weak_­order<const T*, projected<iterator_t<R>, Proj>> Comp = ranges::less> constexpr borrowed_iterator_t<R> ranges::lower_bound(R&& r, const T& value, Comp comp = {}, Proj proj = {});
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Let comp be less{} and proj be identity{} for overloads with no parameters by those names.
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Preconditions: The elements e of [first, last) are partitioned with respect to the expression bool(invoke(comp, invoke(proj, e), value)).
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Returns: The furthermost iterator i in the range [first, last] such that for every iterator j in the range [first, i), bool(invoke(comp, invoke(proj, *j), value)) is true.
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Complexity: At most comparisons and projections.