stl-map

stl库

map

#include<iostream>
#include<map>

using namespace std;
map<char,int> map2;

struct cmp
{
    bool operator()(const char& lhs,const char& rhs)
    {
        return lhs<rhs;
    }
};
bool fncomp(char lhs,char rhs)
{
    return lhs<rhs;
}
int main()
{
    map2['a']=10;
    map2['b']=60;
    map2['c']=50;
    map2['d']=40;
    map2['e']=30;

    map<char,int> map1(map2);
//or
//   map<char,int> map1(map2.begin(),map2.end());

    map<char,int,cmp> map4;

    //bool(*fn_pt)=(char,char)fncomp;
    //map<char,int,bool(*)(char,char)>map5(ft_nt);
    map1.insert({'g',400});             //waring
    map1.insert(make_pair('f',800));
    // map1.insert(map<int,string>::value_type(2,"fff")); //error
    //map1.insert(map<int,char>::value_type('m',2));
    map<char,int>::iterator it;
    for(it=map1.begin(); it!=map1.end(); it++)
    {
        cout<<it->first<<":"<<it->second<<endl;
    }
    cout<<"g=> "<<map1.find('g')->second<<endl;
    cout<<"a=> "<<map1.find('a')->second<<endl;
    // cout<<"i=> "<<map1.find('i')->second<<endl;
    cout<<"m=> "<<map1.find('m')->second<<endl;
    cout<<map1['a']<<endl;
    cout<<map1['q']<<endl;  //0

    map1.clear();
    map1['a']=20;
    map1['b']=62;
    while(!map1.empty())
    {
        cout<<map1.begin()->first<<"=>";
        cout<<map1.begin()->second<<endl;
        map1.erase(map1.begin());
    }
    map1['c']=68;
    map1.erase('c');
    //  cout<<map1.begin()->first<<"=>";
    //  cout<<map1.begin()->second<<endl;

    map1['a']=25;
    map1['b']=67;
    map<char,int>::key_compare key_comp;
    key_comp = map1.key_comp();
    char highset = map1.rbegin()->first;
    it = map1.begin();
    do
    {
        cout<<(*it).first<<"=>"<<(*it).second<<endl;
    }
    while(key_comp((*it++).first,highset));

    cout<<map1.size()<<endl;
    return 0;
}