运行期以索引获取tuple元素-C++11之2

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http://blog.csdn.net/csdnnews/article/details/78859701

//运行期以索引获取tuple元素-C++11之2//需支持C++11及以上标准的编译器，VS2017 15.5.x、CodeBlocks 16.01 gcc 7.2//参见《深入应用C++11:代码优化与工程级应用》p148，祁宇，机械工业出版社，2015年05#include <iostream>#include <tuple>using namespace std;template <typename Arg>void GetArgByIndex(size_t index, tuple<Arg>& tp){ cout << get<0>(tp) << endl; }template <typename Arg, typename... Args>void GetArgByIndex(size_t index, tuple<Arg, Args...>& tp){    if (index < 0 || index >= tuple_size<tuple<Arg, Args...>>::value)    { throw invalid_argument("index is not valid");    }    if (index > 0)        GetArgByIndex(index - 1, (tuple<Args...>&) tp);    else    //index == 0        cout << get<0>(tp) << endl;}int main(void){    auto tp = make_tuple(1, 2, "test", 3);    size_t len = tuple_size<decltype(tp)>::value;    //打印每个元素    for (size_t i = 0; i < len; ++i)    { GetArgByIndex(i, tp);    }    return 0;}

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