Hash_Map

Posted 2020-11-29 abnk

1.

#include <iostream>
#include <map>
#include <hash_map>

// 对该结构体按照xxx排序，在hash_map中存储name和地址
struct Site
{
    Site(const std::string &n, const std::string &i) : name(n), info(i){}
    std::string name;
    std::string info;
    ~Site(){}
};

// 定义哈希函数。这是散列过程中用到的仿函数。
struct hash_site
{
    size_t operator()(const std::string &str)const
    {
        return __gnu_cxx::__stl_hash_string(str.c_str());
    }
};

// 定义定址函数， 查找时需要用到的仿函数。
struct equal_index
{
    // bool operator()(const std::string &siteName, struct Site *site) const
    bool operator()(const std::string &name, const Site * &site) const
    {
        return site->name == name;
    }
};


int main()
{
    // get Site addr by name.   TBD : get name by Site addr
    __gnu_cxx::hash_map <std::string, Site*, hash_site, equal_index> Sites;
    
    Site s1("alex1", "26");
    Site s2("alex2", "27");
    Site s3("alex3", "28");

    Sites["alex1"] = &s1;

    //std::cout << Sites["ccc"]->info << std::endl;
}

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