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I have made the following tuple:
I want to know how should I iterate over it? There is tupl_size(), but reading the documentation, I didn't get how to utilize it. Also I have search SO, but questions seem to be around Boost::tuple .
auto some = make_tuple("I am good", 255, 2.1); 
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So, we have two methods here, to iterate through the values of a tuple: Using Variadic Templates and metaprogramming (No use of std::apply). Using Variadic Templates and std::apply.
The basic idea is to turn tuples into a range with begin() and end() methods to provide iterators. The iterator itself returns a std::variant<...> which can then be visited using std::visit . Read-only access is also supported by passing a const std::tuple<>& to to_range() .
The new std::array and std::tuple containers provide developers with additional ways to manage structured data efficiently.
Using std::queue In other words, std::queue is not meant to be iterated over. If you need to iterate over a std::queue , you can create a copy of it and remove items from the copy, one at a time, using the standard pop function after processing it.
template<class F, class...Ts, std::size_t...Is> void for_each_in_tuple(const std::tuple<Ts...> & tuple, F func, std::index_sequence<Is...>){ using expander = int[]; (void)expander { 0, ((void)func(std::get<Is>(tuple)), 0)... }; } template<class F, class...Ts> void for_each_in_tuple(const std::tuple<Ts...> & tuple, F func){ for_each_in_tuple(tuple, func, std::make_index_sequence<sizeof...(Ts)>()); } Usage:
auto some = std::make_tuple("I am good", 255, 2.1); for_each_in_tuple(some, [](const auto &x) { std::cout << x << std::endl; }); Demo.
std::index_sequence and family are C++14 features, but they can be easily implemented in C++11 (there are many available on SO). Polymorphic lambdas are also C++14, but can be replaced with a custom-written functor.
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