C++中“tuple”(元组)容器详解

tuple容器(元组), 是暗示元组容器, 是不包括任何布局的,快速而低质(粗制滥造, quick and dirty)的, 可以用于函数返回多个返回值;

tuple容器, 可以利用直接初始化, 和"make_tuple()"初始化, 会见元素利用"get<>()"要领, 留意get内里的位置信息, 必需是常量表达式(const expression);

可以通过"std::tuple_size<decltype(t)>::value"获取元素数量; "std::tuple_element<0, decltype(t)>::type"获取元素范例;

假如tuple范例举办较量, 则需要保持元素数量沟通, 范例可以较量, 如沟通范例, 或可以彼此转换范例(int&double);

无法通过普通的要领遍历tuple容器, 因为"get<>()"要领, 无法利用变量获取值;

以下代码包括一些根基的用法, 详见注释;

代码:

/* 
 * CppPrimer.cpp 
 * 
 *  Created on: 2013.12.9 
 *      Author: Caroline 
 */
      
/*eclipse cdt, gcc 4.8.1*/
      
#include <iostream>  
#include <vector>  
#include <string>  
#include <tuple>  
      
using namespace std;  
      
std::tuple<std::string, int>  
giveName(void)  
{  
    std::string cw("Caroline");  
    int a(2013);  
    std::tuple<std::string, int> t = std::make_tuple(cw, a);  
    return t;  
}  
      
int main()  
{  
    std::tuple<int, double, std::string> t(64, 128.0, "Caroline");  
    std::tuple<std::string, std::string, int> t2 =  
            std::make_tuple("Caroline", "Wendy", 1992);  
      
    //返回元素个数  
    size_t num = std::tuple_size<decltype(t)>::value;  
    std::cout << "num = " << num << std::endl;  
      
    //获取第1个值的元素范例  
    std::tuple_element<1, decltype(t)>::type cnt = std::get<1>(t);  
    std::cout << "cnt = " << cnt << std::endl;  
      
    //较量  
    std::tuple<int, int> ti(24, 48);  
    std::tuple<double, double> td(28.0, 56.0);  
    bool b = (ti < td);  
    std::cout << "b = " << b << std::endl;  
      
    //tuple作为返回值  
    auto a = giveName();  
    std::cout << "name: " << get<0>(a)  
            << " years: " << get<1>(a) << std::endl;  
      
    return 0;  
}

输出:

num = 3  
cnt = 128  
b = 1  
name: Caroline years: 2013

作者：csdn博客 Spike_King