输出任意一个tuple的元素

运用C++11中的variadic template我们可以实现输出任意一个tuple元素

代码如下：

#include <iostream>

#include <tuple>

#include <stdio.h>

template <int... >

struct seq {};

template <int N, int... S>

struct genseq : genseq<N - 1, N - 1,S...>

{

};

template <int... S>

struct genseq<0, S...>

{

    typedefseq<S...> type;

};

void show()

{

    std::cout<< std::endl;

}

template <typename T, typename...TRest>

void show(const T& item, constTRest&... rest)

{

    std::cout<< item<< ", ";

    show(rest...);

}

template <typename... T, int...S>

voidunpack_tuple(std::tuple<T...>&tp, seq<S...>sq)

{

   show(std::get<S>(tp)...);

}

template <typename... T>

voidprint_tuple(std::tuple<T...>&tp)

{

    unpack_tuple(tp,typenamegenseq<sizeof...(T)>::type());

}

int main()

{

   std::tuple<int, double, char> tp{123,456.789, 'c'};

   std::tuple<char *, float,std::string> tp1{"test for print tuple", 123.456789," successfully! :)"};

    print_tuple(tp);

    print_tuple(tp1);

    return 0;

}