(C++17) | ||||
| Sequence | ||||
(C++11) | ||||
(C++26) | ||||
(C++26) | ||||
(C++11) | ||||
| Associative | ||||
| Unordered associative | ||||
(C++11) | ||||
(C++11) | ||||
(C++11) | ||||
(C++11) | ||||
| Adaptors | ||||
(C++23) | ||||
(C++23) | ||||
(C++23) | ||||
(C++23) | ||||
| Views | ||||
(C++20) | ||||
(C++23) | ||||
| Tables | ||||
| Iterator invalidation | ||||
| Member function table | ||||
| Non-member function table |
std::pair<iterator, iterator> equal_range(const Key& key); | (1) | (since C++23) (constexpr since C++26) |
std::pair<const_iterator, const_iterator> equal_range(const Key& key)const; | (2) | (since C++23) (constexpr since C++26) |
template<class K> std::pair<iterator, iterator> equal_range(const K& x); | (3) | (since C++23) (constexpr since C++26) |
template<class K> std::pair<const_iterator, const_iterator> | (4) | (since C++23) (constexpr since C++26) |
Returns a range containing all elements with the given key in the container. The range is defined by two iterators, one pointing to the first element that isnot less than the given key and another pointing to the first element greater than the given key.
Alternatively, the first iterator may be obtained withlower_bound(), and the second withupper_bound().
Compare istransparent. It allows calling this function without constructing an instance ofKey.Contents |
| key | - | key value to compare the elements to |
| x | - | alternative value that can be compared toKey |
std::pair containing a pair of iterators defining the wanted range:
Logarithmic in the size of the container.
#include <iostream>#include <flat_map> int main(){conststd::flat_map<int,constchar*> m{{0,"zero"},{1,"one"},{2,"two"}}; auto p= m.equal_range(1);for(auto& q= p.first; q!= p.second;++q)std::cout<<"m["<< q->first<<"] = "<< q->second<<'\n'; if(p.second== m.find(2))std::cout<<"end of equal_range (p.second) is one-past p.first\n";elsestd::cout<<"unexpected; p.second expected to be one-past p.first\n"; auto pp= m.equal_range(-1);if(pp.first== m.begin())std::cout<<"pp.first is iterator to first not-less than -1\n";elsestd::cout<<"unexpected pp.first\n"; if(pp.second== m.begin())std::cout<<"pp.second is iterator to first element greater-than -1\n";elsestd::cout<<"unexpected pp.second\n"; auto ppp= m.equal_range(3);if(ppp.first== m.end())std::cout<<"ppp.first is iterator to first not-less than 3\n";elsestd::cout<<"unexpected ppp.first\n"; if(ppp.second== m.end())std::cout<<"ppp.second is iterator to first element greater-than 3\n";elsestd::cout<<"unexpected ppp.second\n";}
Output:
m[1] = oneend of equal_range (p.second) is one-past p.firstpp.first is iterator to first not-less than -1pp.second is iterator to first element greater-than -1ppp.first is iterator to first not-less than 3ppp.second is iterator to first element greater-than 3
| finds element with specific key (public member function)[edit] | |
| checks if the container contains element with specific key (public member function)[edit] | |
| returns the number of elements matching specific key (public member function)[edit] | |
| returns an iterator to the first elementgreater than the given key (public member function)[edit] | |
| returns an iterator to the first elementnot less than the given key (public member function)[edit] | |
| returns range of elements matching a specific key (function template)[edit] |
