| [section:lower_bound lower_bound] |
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| [heading Prototype] |
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| `` |
| template<class ForwardRange, class Value> |
| typename range_iterator<ForwardRange>::type |
| lower_bound(ForwardRange& rng, Value val); |
| |
| template< |
| range_return_value re, |
| class ForwardRange, |
| class Value |
| > |
| typename range_return<ForwardRange, re>::type |
| lower_bound(ForwardRange& rng, Value val); |
| `` |
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| [heading Description] |
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| The versions of `lower_bound` that return an iterator, returns the first iterator in the range `rng` such that: |
| without predicate - `*i < value` is `false`, |
| with predicate - `pred(*i, value)` is `false`. |
| |
| `end(rng)` is returned if no such iterator exists. |
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| The versions of `lower_bound` that return a `range_return`, defines `found` in the same manner as the returned iterator described above. |
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| [heading Definition] |
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| Defined in the header file `boost/range/algorithm/lower_bound.hpp` |
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| [heading Requirements] |
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| [*For the non-predicate versions:] |
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| * `ForwardRange` is a model of the __forward_range__ Concept. |
| * `Value` is a model of the `LessThanComparableConcept`. |
| * The ordering of objects of type `Value` is a [*/strict weak ordering/], as defined in the `LessThanComparableConcept` requirements. |
| * `ForwardRange`'s value type is the same type as `Value`. |
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| [*For the predicate versions:] |
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| * `ForwardRange` is a model of the __forward_range__ Concept. |
| * `BinaryPredicate` is a model of the `StrictWeakOrderingConcept`. |
| * `ForwardRange`'s value type is the same type as `Value`. |
| * `ForwardRange`'s value type is convertible to both of `BinaryPredicate`'s argument types. |
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| [heading Precondition:] |
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| [*For the non-predicate versions:] |
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| `rng` is sorted in ascending order according to `operator<`. |
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| [*For the predicate versions:] |
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| `rng` is sorted in ascending order according to `pred`. |
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| [heading Complexity] |
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| For ranges that model the __random_access_range__ concept the complexity is `O(log N)`, where `N` is `distance(rng)`. |
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| For all other range types the complexity is `O(N)`. |
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| [endsect] |
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