tuple不定值數組

目錄

1、tuple

2、函數

3、測試

---

1、tuple

tuple擴展了pair將兩個元素看成一個單元的功能，實現了可以將任意數量元素當作一個單元的功能。

2、函數

tuple<T1,T2...Tn> t;            以n個給定類型的元素建立tuple
tuple<T1,T2...Tn> t(v1,v2...vn);建立tuple，並初始化
tuple<T1,T2> t(pair);           建立一個tuple，帶兩個元素
t  = t2;                        將值t2賦值給t
t = pair;                       將pair 賦值給帶兩個元素的tuple
t1 == t2;                       比較所有元素
t1 != t2	
t1 < t2	
t1 > t2	
t1 <= t2	
t1 >= t2	
t1.swap(t2);	
swap(t1,t2);	
make_tuple(v1,v2...);           以傳入值類型建立tuple
tie（ref(1)...;                 建立reference構成的tuple

3、測試

#include <iostream>
#include <tuple>
#include <string>
using namespace std;

template<int Idx, int Max, typename... Args>
struct PRINT_TUPLE {
	static void print(ostream &os, const tuple<Args...>& t)
	{
		os << get<Idx>(t) << (Idx + 1 == Max ? "" : ",");
		//遞歸
		PRINT_TUPLE<Idx + 1, Max, Args...>::print(os, t);
	}
};

//遞歸的結束條件
template <int Max, typename... Args>
struct PRINT_TUPLE<Max, Max, Args...>
{
	static void print(ostream &os, const tuple<Args...>& t)
	{

	}
};

//重載操作運算符<<
template <typename... Args>
ostream& operator << (ostream& os, const tuple<Args...>& t)
{
	os << "[";
	PRINT_TUPLE<0, sizeof...(Args), Args...>::print(os, t);
	return os << "]";
}

int main()
{
	//創建
	tuple<int, char, string> t;
	t = make_tuple(1, 'a', "ABC");
	cout << get<0>(t) << ends << get<1>(t) << ends << get<2>(t).c_str() << endl;

	//取值
	int a = 0;
	char ch1 = ' ';
	string str;
	tie(a, ch1, str) = t;
	cout << a << ends << ch1 << ends << str.c_str() << endl;

	//不允許這種操作，不允許隱式轉換
	//vector<tuple<int, char, string>> v{ { 1, 'a', "ABC" }，{ 2, 'b', "DEF" } };
	
	cout << t << endl;

	//獲取元素類型
	tuple_element<0, decltype(t)>::type ages;  
	//獲取元素數目
	cout << tuple_size<decltype(t)>::value << endl;
	system("pause");
}