C++中map数组的排序,删除某一个值等操作
#include<iostream>
#include<algorithm>
#include<stdio.h>
#include <vector>
#include<string>
#include<map>
#include <functional> // std::greater
using namespace std;
bool cmp(const pair<string, int>& a, const pair<string, int>& b) {
return a.second < b.second;
}
struct CmpByKeyLength {
bool operator()(const string& k1, const string& k2)const {
return k1.length() < k2.length();
}
};
void map_sort()
{
//1、map这里指定less作为其默认比较函数(对象),就是默认按键值升序排列
// map<string, int> name_score_map;
// 2、可以自定义,按照键值升序排列,注意加载
// #include <functional> // std::greater
// map<string, int, greater<string>> name_score_map;
//3、按照自定义内容进行排序,比如字符串的长度
map<string, int, CmpByKeyLength> name_score_map;
name_score_map["LiMin"] = 90;
name_score_map["ZiLinMi"] = 79;
name_score_map["BoB"] = 92;
name_score_map.insert(make_pair("Bing", 99));
name_score_map.insert(make_pair("Albert", 86));
map<string, int>::iterator iter;
for (iter = name_score_map.begin(); iter != name_score_map.end(); ++iter) {
cout << (*iter).first <<" "<<(*iter).second<< endl;
}
}
void map_vec_sort()
{
//1、map这里指定less作为其默认比较函数(对象),就是默认按键值升序排列
map<string, int> name_score_map;
name_score_map["LiMin"] = 90;
name_score_map["ZiLinMi"] = 79;
name_score_map["BoB"] = 92;
name_score_map.insert(make_pair("Bing", 99));
name_score_map.insert(make_pair("Albert", 86));
//输出添加的内容
map<string, int>::iterator iter;
//for (iter = name_score_map.begin(); iter != name_score_map.end(); ++iter) {
// cout << (*iter).first << " " << (*iter).second << endl;
//}
//cout << endl;
// 将map中的内容转存到vector中
vector<pair<string, int>> vec(name_score_map.begin(), name_score_map.end());
//对线性的vector进行排序
sort(vec.begin(), vec.end(), cmp);
for (int i = 0; i < vec.size(); ++i)
cout << vec[i].first << " " << vec[i].second << endl;
}
void map_delete()
{
map<string, string>data;
data["d"] = "limgn";
data["c"] = "delrg";
data["r"] = "abrf";
/////根据键就是index进行删除
data.erase("c");
if (data.find("c") == data.end())
{
cout << "delte index success" << endl;
}
//////根据后面的值进行删除
for (auto it = data.begin(); it != data.end();)
{
if (it->second == "abrf")
{
data.erase(it++);
cout << "delete value" << endl;
}
else
it++;
}
if (data.find("r") == data.end())
{
cout << "delete value suceess" << endl;
}
}
int main()
{
cout << "map 直接进行排,初始化就拍好" << endl;
map_sort();
cout << endl;
cout << "map 利用vector进行排序" << endl;
map_vec_sort();
cout << endl << "map元素的删除,利用index或者value,注意循环" << endl;
////删除
map_delete();
system("pause");
return 0;
}