无序关联容器的使用

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unordered_set

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#include <iostream>
#include <unordered_map>    //map映射表 存储的key-value
#include <unordered_set>    //set集合，只存储key
#include <string>
using namespace std;

int main()
{
    //set的使用
    unordered_set<int> set1;
    //增加
    set1.insert(1010);
    set1.insert(1020);
    set1.insert(1030);
    //查询
    auto it=set1.find(1010);
    if(it==set1.end())
        cout<<"no find 1010"<<endl;
    else
        cout<<*it<<endl;
    //删除
    set1.erase(1010);
    it=set1.find(1010);
    if(it==set1.end())
        cout<<"no find 1010"<<endl;
    else
        cout<<*it<<endl;
    //遍历
    for(it=set1.begin();it!=set1.end();++it)
        cout<<*it<<" ";
    cout<<endl;
    for(auto &key:set1)
        cout<<key<<" ";
    cout<<endl;
    return 0;
}

unordered_map

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#include <iostream>
#include <unordered_map>    //map映射表 存储的key-value
#include <unordered_set>    //set集合，只存储key
#include <string>
using namespace std;

int main()
{
    //map的使用
    unordered_map<int,string>map1;
    //增加
    map1.insert({10,"zhangwei"});
    map1.insert({20,"dali"});
    map1[30]="tanyishan";
    //查询,it这里是迭代器类型，指向的是map里面的元素，Pair对象。
    auto it=map1.find(10);
    if(it==map1.end())
        cout<<"10 not exist"<<endl;
    else
        cout<<"key:"<<it->first<<" value:"<<it->second<<endl;
    //删除
    map1.erase(10);
    it=map1.find(10);
    if(it==map1.end())
        cout<<"10 not exist"<<endl;
    else
        cout<<"key:"<<it->first<<" value:"<<it->second<<endl;
    //遍历
    for(it=map1.begin();it!=map1.end();++it)
        cout<<it->first<<" "<<it->second<<endl;
    for(auto it : map1)
        cout<<it.first<<" "<<it.second<<endl;
    return 0;
}