Header that defines the unordered_map and unordered_multimap container classes: Classes unordered_map Unordered Map (class template ) unordered_multimap Unordered Multimap (class template ) Functions begin Iterator to beginning (function template ) end Iterator to end (function template )C++...
( unordered_multimap<K, T, H, P, A>& c, Predicate pred); namespace pmr { template<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>> using unordered_map = std::unordered_map<Key, T, Hash, Pred, polymorphic_allocator<pair<const Key, T>>>; template<...
std::unordered_map<int, std::string> c = {{1, "one"}, {2, "two"}, {3, "three"}, {4, "four"}, {5, "five"}, {6, "six"}}; // 从 c 擦除所有奇数 for(auto it = c.begin(); it != c.end(); ) //使用std::unordered_map<int,std::string>::iterator来表明 if(it-...
unordered_map 采用了扩容的机制,当负载因子 (load factor) 超过了阈值,就会进行一次扩容。负载因子的计算方法是总键值对数除以桶数。扩容的时候,会重新计算散列,重新放入到桶里。 cplusplus 文档:https://www.cplusplus.com/reference/unordered_map/unordered_map/ 代码声明 从以下的代码中,我们可以看到 unordered_m...
unordered_map 是关联容器,含有带唯一键的键-值 pair 。搜索、插入和元素移除拥有平均常数时间复杂度。 元素在内部不以任何特定顺序排序,而是组织进桶中。元素放进哪个桶完全依赖于其键的哈希。这允许对单独元素的快速访问,因为一旦计算哈希,则它准确指代元素所放进的桶。
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std::unordered_map template<class...Args> std::pair<iterator,bool>emplace(Args&&...args); (since C++11) Inserts a new element into the container constructed in-place with the givenargs, if there is no element with the key in the container. ...
From cppreference.com Containers library std::unordered_map Member types Member functions unordered_map::unordered_map unordered_map::~unordered_map unordered_map::operator= unordered_map::get_allocator Iterators unordered_map::beginunordered_map::cbegin ...
// unordered_map::begin/end example#include <iostream>#include <unordered_map>intmain () { std::unordered_map<std::string,std::string> mymap; mymap = {{"Australia","Canberra"},{"U.S.","Washington"},{"France","Paris"}}; std::cout <<"mymap contains:";for(autoit = mymap.begin...
A reference to the data value of the element found.RemarksIf the argument key value isn't found, then the function throws an object of class out_of_range.ExampleC++ Copy // unordered_map_at.cpp // compile with: /EHsc #include <unordered_map> #include <iostream> typedef std::unordered...