C ++问题将数组存储在哈希表中 [英] C++ Problems Store array in hashtable

问题描述

我正在通过使用Q学习算法来帮助代理人获得奖励来开展关于实现C ++程序的研究。

我正在尝试使用Hashtable存储我的州和行动。
我不熟悉C ++编程...

我想要做的是像使用哈希表存储数组。
但我找不到正确的方法存储它...哈希表表示它是数组的错误类型。

  using namespace std; 
 int state [2] = {0,0}; 
 unordered_map< string，int>哈希表; 
 hashtable.emplace（State1，state）; 
 cout<<< 状态1是：< hashtable [State1]<< ENDL; cin.get（）; 
  

 错误C2664'std： ：对< const _Kty，_Ty> :: pair（std :: pair< const _Kty，_Ty&&&&）'：不能将参数2从int [2]转换为const int&'myproject c： \程序文件（x86）\microsoft visual studio 
  

14.0 \vc\include\ xmemory0 737

C ++ HashTable可以将数组存储为键和值吗？
如果它没有任何方法来存储数组在表中？它像Python字典功能一样。

谢谢！

解决方案

p>有一些unordered_map的提示可以帮助你。

  #include< iostream> 
 #include< unordered_map> 
 #include< string> 
 #include< vector> 
使用命名空间std; 
 
 int main（）{
 //构造函数
 unordered_map< string，int> hashTable = {
 {a，123}，
 {b，456}，
 {c，789} 
}; 
 
 // update 
 hashTable [a] = 1; 
 //添加新条目
 hashTable [d] = 2; 
 hashTable.insert（{e，111}）; 
 //迭代并打印unordered_map 
的键和值（const auto& n：hashTable）
 cout<<< Key：<< n.first< \tValue：<< n.second < ENDL; 
 //按键输出值
 cout<<< d的值为：< hashTable [d]<< ENDL; 
 
 //初始向量
向量< int>状态{1,2,3,4,5,6,7}; 
 states.push_back（8）; 
 
 //将向量添加到unordered_map 
 unordered_map< string，vector< int>> HT; 
 ht [state1] =状态; 
 ht.insert（{c，vector< int> {1,1,1,1}}）; 
 
 cout<<< 关键字在ht中的c的值< ENDL; （auto& v：ht [c]）
 
 cout<< v< \t; 
 cout<<< ENDL; 
 
 / * 
 *将数组放入unordered_map 
 * / 
 int state1 [3] = {0，1，2}; 
 int state2 [2] = {3，4}; 
 int state3 [4] = {5，6，7，8}; 
 
 //声明地图存储int指针值
 unordered_map< string，int *> u_map; 
 
 //添加到unordered_map 
 u_map [a] = state1; 
 u_map [b] = state2; 
 u_map.insert（{c，state3}）; 
 
 // update 
 u_map [b] = state3; 
 
 //获取数组的指针
 auto s1 = u_map [a]; 
 int * s2 = u_map [b]; 
 
 //访问数组
中的val cout<<< a的值是：<< s2 [0]< ENDL; 
 
 size_t size = sizeof（s1）/ sizeof（s1 [0]）; （int i = 0; i< = size; ++ i）
 {
 cout< val< i< 是：< s1 [i]<< ENDL; 
} 
 return 0; 
} 
  

输出：

<$密钥：d值：2
密钥：b值：456
密钥：c值：789
密钥：a值：1
d的值是：2
键a的值是：5
val 0是：0
val 1是：1
val 2是：2

更新：

 修复使用类模板'vector'需要模板参数
更新将数组添加到地图
  

I am currently doing a research about implement a C++ programe by using Q-learning algorithm to help the agent get the reward.

I am trying to use the Hashtable to store my states and Actions. I am not familiar with the C++ programming...

What i am trying to do is like using hashtable to store the Arrays. but i can not find the right way to store it... the hashtable said it is an error type of the array.

using namespace std;
int state[2] = {0,0};
unordered_map<string, int> hashtable;
hashtable.emplace("State1", state);
cout << "the State of State1 is :" << hashtable["State1"] << endl; cin.get();

Error C2664   'std::pair<const _Kty,_Ty>::pair(std::pair<const _Kty,_Ty> &&)': cannot convert argument 2 from 'int [2]' to 'const int &'  myproject   c:\program files (x86)\microsoft visual studio

14.0\vc\include\xmemory0 737

Does C++ HashTable can Store an Array as Key and Value? If it Doesn't is there any way to store an Array in a table? which like the Python dictionary function....

Thanks!

解决方案

there are some tips of unordered_map which can help u.

#include <iostream>
#include <unordered_map>
#include <string>
#include <vector>
using namespace std;

int main() {
    // constructor
    unordered_map<string, int> hashTable = {
            {"a", 123},
            {"b", 456},
            {"c", 789}
    };

    // update
    hashTable["a"] = 1;
    // add new entry
    hashTable["d"] = 2;
    hashTable.insert({"e", 111});
    // Iterate and print keys and values of unordered_map
    for (const auto& n : hashTable )
        cout << "Key: " << n.first << "\tValue: " << n.second << endl;
    // Output values by key
    cout << "The value of d is :" << hashTable["d"] << endl;

    // init vector
    vector<int> states{1,2,3,4,5,6,7};
    states.push_back(8);

    // add vector into unordered_map
    unordered_map<string, vector<int>> ht;
    ht["state1"] = states;
    ht.insert({"c", vector<int>{1,1,1,1}});

    cout << "Values which key is 'c' in ht" << endl;
    for(auto& v : ht["c"])
        cout << v << "\t";
    cout << endl;

    /*
     * put array into unordered_map
     */
    int state1[3] = {0, 1, 2};
    int state2[2] = {3, 4};
    int state3[4] = {5, 6, 7, 8};

    // declare map to store int pointer value
    unordered_map<string, int*> u_map;

    // add into unordered_map
    u_map["a"] = state1;
    u_map["b"] = state2;
    u_map.insert({"c", state3});

    // update
    u_map["b"] = state3;

    // get pointer of array
    auto s1 = u_map["a"];
    int* s2 = u_map["b"];

    // accesses val in array
    cout << "Value of key a is: "<< s2[0] << endl;

    size_t size = sizeof(s1)/sizeof(s1[0]);
    for (int i = 0; i <= size ; ++i) {
        cout << "val " << i << " is: "<< s1[i] << endl;
    }
    return 0;
}

output:

Key: d  Value: 2
Key: b  Value: 456
Key: c  Value: 789
Key: a  Value: 1
The value of d is :2
Value of key a is: 5
val 0 is: 0
val 1 is: 1
val 2 is: 2

update:

fix use of class template 'vector' requires template arguments
update for adding array into map

这篇关于C ++问题将数组存储在哈希表中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！