C++ 使用 pair<int, int> 作为映射的键
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Using pair<int, int> as key for map
提问by sccs
Based on a previous question, I am trying to create a map using a pair of integers as a key i.e. map<pair<int, int>, int>and I've found information on how to insert:
基于上一个问题，我正在尝试使用一对整数作为键创建一个映射，即map<pair<int, int>, int>我找到了有关如何插入的信息：
#include <iostream>
#include <map>
using namespace std;
int main ()
{
map<pair<int, int>, int> mymap;
mymap.insert(make_pair(make_pair(1,2), 3)); //edited
}
but I can't seem to access the element! I've tried cout << mymap[(1,2)] << endl;but it shows an error, and I can't find information on how to access the element using the key. Am I doing something wrong?
但我似乎无法访问该元素！我已经尝试过，cout << mymap[(1,2)] << endl;但它显示了一个错误，而且我找不到有关如何使用密钥访问元素的信息。难道我做错了什么？
采纳答案by andre
you need a pair as a key cout << mymap[make_pair(1,2)] << endl;What you currently have cout << mymap[(1,2)] << endl;is not the correct syntax.
您需要一对作为键cout << mymap[make_pair(1,2)] << endl;您目前拥有cout << mymap[(1,2)] << endl;的语法不正确。
回答by Louis Brandy
mymap[make_pair(1,2)]
mymap[make_pair(1,2)]
or, with compiler support:
或者，在编译器支持下：
mymap[{1,2}]
mymap[{1,2}]
回答by Chandra Shekhar
Please find the code for the reference:
请找到参考代码：
#include<iostream>
#include<map>
using namespace std;
int main()
{
map<pair<int ,int> ,int > m;
m.insert({{1, 2}, 100});
cout << m[{1, 2}];
}
