24 Algorithms library [algorithms]

24.7 Sorting and related operations [alg.sorting]

24.7.3 Binary search [alg.binary.search]

24.7.3.1 lower_­bound [lower.bound]

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); namespace ranges { template<ForwardIterator I, Sentinel<I> S, class T, class Proj = identity, IndirectStrictWeakOrder<const T*, projected<I, Proj>> Comp = ranges::less<>> constexpr I lower_bound(I first, S last, const T& value, Comp comp = {}, Proj proj = {}); template<ForwardRange R, class T, class Proj = identity, IndirectStrictWeakOrder<const T*, projected<iterator_t<R>, Proj>> Comp = ranges::less<>> constexpr safe_iterator_t<R> lower_bound(R&& r, const T& value, Comp comp = {}, Proj proj = {}); }
Let comp be less{} and proj be identity{} for overloads with no parameters by those names.
Requires: The elements e of [first, last) shall be partitioned with respect to the expression bool(invoke(comp, invoke(proj, e), value)).
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.
Complexity: At most comparisons and projections.