检查一个std::map对象是否有自定的key值函数(两种处理): //方式1,使用algorithm的算法库 template<typenameT_KEY,typenameT_VALUE> boolHasMapKey_1(std::map<T_KEY,T_VALUE>&tMap,T_KEYtKey) { std::map<T_KEY,T_VALUE>::iteratorit=std::find_if(tMap.begin(),tMap.end(), [tKey](std::pair...
std::map插入已存在的key时,key对应的内容不会被更新,如果不知道这一点,可能会造成运行结果与预期的不一致 “Because element keys in amapare unique, the insertion operation checks whether each inserted element has a key equivalent to the one of an element already in the container, and if so, the...
iostream> #include <map> #include <vector> #include <string> template <typename Key, typename Value> class MyMap : public std::map<Key, Value> { public: // 检查键是否存在 bool hasKey(const Key& key) const { return this->find(key) !
if (iter != ss.end()) { cout << "Has find key." << endl; cout << "KEY:"; print(iter->first); cout << ",VALUE:" << iter->second << endl; }else{ cout << "Can't find key." << endl; } map<int,int> kk; kk.insert(std::pair<int,int>(1,1)); kk.insert(std::...
cout << "Has find key." << endl;cout << "KEY:";print(iter->first);cout << ",VALUE:" << iter->second << endl;}else{ cout << "Can't find key." << endl;} map<int,int> kk;kk.insert(std::pair<int,int>(1,1));kk.insert(std::pair<int,int>(1,2));kk.insert(std::...
std::map<Key,T,Compare,Allocator>::insert_range From cppreference.com <cpp |container |map Containers library std::map template<container-compatible-range<value_type>R> voidinsert_range(R&&rg); (since C++23) Inserts a copy of each element ofrgif and only if there is no element ...
("d","ddd");// emplace with duplicate key has no effectm.emplace("d","DDD");// uses pair's piecewise constructorm.emplace(std::piecewise_construct,std::forward_as_tuple("c"),std::forward_as_tuple(10,'c'));// an alternative is: m.try_emplace("c", 10, 'c');for(constauto...
#if _HAS_CPP0X #else /* _HAS_CPP0X */ #if _HAS_STRICT_CONFORMANCE void erase(const_iterator _Where) { // erase element at _Where _Mybase::erase(_Where); } size_type erase(const key_type& _Keyval) { // erase and count all that match _Keyval ...
// Use a custom KeyEqual which has an is_transparent member type tsl::sparse_map<employee, int, hash_employee, equal_employee> map2; map2.insert({employee(4, "Johnny Doe"), 2004}); // 2004 std::cout << map2.at(4) << std::endl; ...
cout << "Has find key." << endl; cout << "KEY:"; print(iter->first); cout << ",VALUE:" << iter->second << endl; }else{ cout << "Can't find key." << endl; } map<int,int> kk; kk.insert(std::pair<int,int>(1,1)); ...