| [section:equal_range equal_range] |
| |
| [heading Prototype] |
| |
| `` |
| template< |
| class ForwardRange, |
| class Value |
| > |
| std::pair<typename range_iterator<ForwardRange>::type, |
| typename range_iterator<ForwardRange>::type> |
| equal_range(ForwardRange& rng, const Value& val); |
| |
| template< |
| class ForwardRange, |
| class Value |
| > |
| std::pair<typename range_iterator<const ForwardRange>::type, |
| typename range_iterator<const ForwardRange>::type> |
| equal_range(const ForwardRange& rng, const Value& val); |
| |
| template< |
| class ForwardRange, |
| class Value, |
| class SortPredicate |
| > |
| std::pair<typename range_iterator<ForwardRange>::type, |
| typename range_iterator<ForwardRange>::type> |
| equal_range(ForwardRange& rng, const Value& val, SortPredicate pred); |
| |
| template< |
| class ForwardRange, |
| class Value, |
| class SortPredicate |
| > |
| std::pair<typename range_iterator<const ForwardRange>::type, |
| typename range_iterator<const ForwardRange>::type> |
| equal_range(const ForwardRange& rng, const Value& val, SortPredicate pred); |
| `` |
| |
| [heading Description] |
| |
| `equal_range` returns a range in the form of a pair of iterators where all of the elements are equal to `val`. If no values are found that are equal to `val`, then an empty range is returned, hence `result.first == result.second`. For the non-predicate versions of `equal_range` the equality of elements is determined by `operator<`. |
| For the predicate versions of `equal_range` the equality of elements is determined by `pred`. |
| |
| [heading Definition] |
| |
| Defined in the header file `boost/range/algorithm/equal_range.hpp` |
| |
| [heading Requirements] |
| |
| [*For the non-predicate versions:] |
| |
| * `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`. |
| |
| [*For the predicate versions:] |
| |
| * `ForwardRange` is a model of the __forward_range__ Concept. |
| * `SortPredicate` is a model of the `StrictWeakOrderingConcept`. |
| * `ForwardRange`'s value type is the same as `Value`. |
| * `ForwardRange`'s value type is convertible to both of `SortPredicate`'s argument types. |
| |
| [heading Precondition:] |
| |
| For the non-predicate versions: `rng` is ordered in ascending order according to `operator<`. |
| |
| For the predicate versions: `rng` is ordered in ascending order according to `pred`. |
| |
| [heading Complexity] |
| |
| For random-access ranges, the complexity is `O(log N)`, otherwise the complexity is `O(N)`. |
| |
| [endsect] |
| |
| |
