C++11--Tuple类<tuple>

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#include "stdafx.h"
#include <iomanip>
#include <condition_variable>
#include <deque>
#include <functional>
#include <iostream>
#include <fstream>
#include <thread>
#include <map>
#include <unordered_map>
#include <string>
#include <mutex>

#include <algorithm>
#include <sstream>
#include <future>
#include <tuple>


#include <random>
using namespace std;

struct Node {
    char id; 
    int value;
    Node(char i, int v) : id(i), value(v) {}
    Node() : id(0), value(‘z‘) {}
};

int main() {
   tuple<int, string, char> t(32, "Penny wise", ‘a‘);
   tuple<int, string, char> t = {32, "Penny wise", ‘a‘};  // 编译不过，构造函数是explicit的

   cout << get<0>(t) << endl;
   cout << get<1>(t) << endl;
   cout << get<2>(t) << endl;

   get<1>(t) = "Pound foolish";
   cout << get<1>(t) << endl;

   string& s = get<1>(t);
   s = "Patience is virtue"; 
   cout << get<1>(t) << endl;   
   //get<3>(t);  // 编译不过，t只有3个字段
   // get<1>(t) 类似于vector中的t[1]

   int i = 1;
   //get<i>(t); // 编译不过，i必须是编译时常数


   tuple<int, string, char> t2;  // 默认构造
   t2 = tuple<int, string, char>(12, "Curiosity kills the cat", ‘d‘); 
   t2 = make_tuple(12, "Curiosity kills the cat", ‘d‘); 

   if (t > t2) {  // 词典比较
       cout << "t is larger than t2" << endl;
   }

   t = t2;  // 逐成员拷贝


// Tuple可以储存引用!!  诸如vector这样的STL容器不能。  Pair也可以
   string st = "In for a penny";
   tuple<string&> t3(st);  
   //auto t3 = make_tuple(ref(st));  // 同上
   get<0>(t3) = "In for a pound";  // st has "In for a pound"
   cout << st << endl;
   t2 = make_tuple(12, "Curiosity kills the cat", ‘d‘); 
   int x;
   string y;
   char z;
   std::make_tuple(std::ref(x), std::ref(y), std::ref(z)) = t2;  // 将t2赋值给to x, y, z
   std::tie(x,y,z) = t2;  // 同上
   std::tie(x, std::ignore, z) = t2;  // 好处是tie可以有选择，get<1>(t2) is ignored

// 其他特性
   auto t4 = std::tuple_cat( t2, t3 );  // t4是t2和t3级联之后的结果tuple<int, string, char, string>
   cout << get<3>(t4) << endl;  // "In for a pound" 

   // 类型特征 type traits
   cout << std::tuple_size<decltype(t4)>::value << endl;  // Output: 4
   std::tuple_element<1, decltype(t4)>::type dd; // dd是string类型
   
}



// tuple vs struct

tuple<string, int> getNameAge() { 
   return make_tuple("Bob", 34);
}

int main() {
   struct Person { string name; int age; } p;
   tuple<string, int> t;

   cout << p.name << " " << p.age << endl; //用struct有利于代码review
   cout << get<0>(t) << " " << get<1>(t) << endl; //tuple方便

   // 作为单次使用的结构来传输一组数据
   string name;
   int age;
   tie(name, age) = getNameAge();

   // 比较tuples
   tuple<int, int, int> time1, time2; // hours, minutes, seconds
   if (time1 > time2) 
      cout << " time1 is a later time";

   // 多索引的map
   map<tuple<int,int,int>, string> timemap;
   timemap.insert(make_pair(make_tuple(12, 2, 3), "Game start"));
    cout << timemap[make_tuple(2,3,4)]; 
   unordered_map<tuple<int,int,int>, string> timemap;

   // 数据换顺序Little trick
   int a, b, c;
   tie(b, c, a) = make_tuple(a, b, c);

}

//不要滥用tuple，一旦发现tuple一再使用，考虑定义struct

C++11--Tuple类<tuple>

标签：turn   UNC   func   make   --   person   random   其他   decltype   

原文地址：https://www.cnblogs.com/logchen/p/10199934.html