用法匯總

insert	插入一個元素
size	獲得map中元素的個數
max_size	獲得map所能容納的元素個數
count	判斷是否存在某個key，存在為返回1
find	查找某個key
erase	刪除指定的元素
clear	清空map
empty	判斷map是否為空
begin	獲取map的第一個元素，一般遍歷的時候用
end	獲取map的最后一個元素，一般遍歷的時候用
rbegin	獲取map的第一個元素，一般倒序遍歷時候用
rend	獲取map的最后一個元素，一般倒序遍歷時候用
value_comp	Retrieves a copy of the comparison object that is used to order element values in a map.
lower_bound	Returns an iterator to the first element in a map that has a key value that is equal to or greater than that of a specified key.
upper_bound	Returns an iterator to the first element in a map that has a key value that is greater than that of a specified key.
swap	Exchanges the elements of two maps.
equal_range	Returns a pair of iterators. The first iterator in the pair points to the first element in a map with a key that is greater than a specified key. The second iterator in the pair points to the first element in the map with a key that is equal to or greater than the key.
get_allocator	Returns a copy of the allocator object that is used to construct the map.
key_comp	Returns a copy of the comparison object that used to order keys in a?

用法示例

// base define std::map <std::string, std::string> sColleagueMap;// 插入元素 sColleagueMap.insert( std::pair<std::string, std::string>("rao", "haijun") ); sColleagueMap.insert( std::pair<std::string, std::string>("zhao", "jingjing") ); sColleagueMap.insert( std::pair<std::string, std::string>("fan", "junjie") );// 訪問指定元素 std::cout<<sColleagueMap.at("rao")<<std::endl;// 判斷map中是否包含某個元素 std::cout<<sColleagueMap.count("rao")<<std::endl;// 查找map中是否包含某個元素 auto findIt = sColleagueMap.find("fan"); if(findIt != sColleagueMap.end() ){ std::cout<<"find the element:"<<findIt->first<<findIt->second<<std::endl; }// 遍歷元素(不允許修改) 從前到后 C++11標準 auto sCollItConst = sColleagueMap.cbegin(); for(; sCollItConst!=sColleagueMap.cend(); ++sCollItConst){ std::cout<<sCollItConst->first<<sCollItConst->second<<std::endl; }// 遍歷元素(不允許修改) 從后到前 C++11標準 auto sCollItConstr = sColleagueMap.crbegin(); for(; sCollItConstr!=sColleagueMap.crend(); ++sCollItConstr){ std::cout<<sCollItConstr->first<<sCollItConstr->second<<std::endl; }// 遍歷元素(可以修改)從前到后 std::map<std::string, std::string>::iterator sCollIt = sColleagueMap.begin(); for(; sCollIt!=sColleagueMap.end(); ++sCollIt){ if(sCollIt->first == "rao"){ sCollIt->second = "yuke"; } std::cout<<sCollIt->first<<sCollIt->second<<std::endl; } // 遍歷元素(可以修改)從后到前 std::map<std::string, std::string>::reverse_iterator sCollItR = sColleagueMap.rbegin(); for(; sCollItR!=sColleagueMap.rend(); ++sCollItR){ if(sCollItR->first == "rao"){ sCollItR->second = "zhihao"; } std::cout<<sCollItR->first<<sCollItR->second<<std::endl; } // 清空所有元素 sColleagueMap.clear(); std::cout<<sColleagueMap.size()<<std::endl;// 判斷map的所能hold到的最大element個數 std::cout<<"max:"<<sColleagueMap.max_size()<<std::endl; char *pNew = new char[1024*1024*1024]; if(!pNew){ std::cout<<"malloc memory error!"<<std::endl; } std::cout<<"max:"<<sColleagueMap.max_size()<<std::endl; delete[] pNew; // 判斷是否為空 std::cout<<sColleagueMap.empty()<<std::endl;

轉載于:https://www.cnblogs.com/p4759521/articles/5898914.html

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