C++中的unordered_map用法

#include <unordered_map>

unordered_map<KeyType, ValueType> myMap; // 声明一个空的 unordered_map
unordered_map<string, int> myMap = {{"apple", 5}, {"banana", 10}}; // 声明并初始化一个包含键值对的 unordered_map

unordered_map<string, int> myMap;
myMap.insert(make_pair("apple", 5)); // 插入键值对
myMap.emplace("banana", 10); // 插入键值对（C++11 特性）
int value1 = myMap["apple"]; // 使用 [] 运算符访问元素
int value2 = myMap.at("banana"); // 使用 at 函数访问元素

unordered_map<string, int> myMap = {{"apple", 5}, {"banana", 10}};
myMap.erase("apple"); // 删除键为 "apple" 的元素

unordered_map<string, int> myMap = {{"apple", 5}, {"banana", 10}};
auto it = myMap.find("apple");
if (it != myMap.end()) {
    cout << "Found: " << it->first << " -> " << it->second << endl;
} else {
    cout << "Not found" << endl;
}

unordered_map<string, int> myMap = {{"apple", 5}, {"banana", 10}};
for (auto it = myMap.begin(); it != myMap.end(); ++it) {
    cout << it->first << " -> " << it->second << endl;
}