c++17

I want to map a number to a type. For this example I'll make a function that maps a sizeof() result onto a signed primitive type. I am wondering if there is a better way of doing what I did below in modern C++, which is to take a templated value and convert it into a type. Right now this works in converting a size to a known type, but I can't seem to find anything in the standard library that does what I want. Have I missed something? If not, is there a better way of doing this or cleaning up this code? For example if somehow in the future we end up having 128 bit types, this wouldn't support

In Modern C++, is there a way to do safe navigation? For example, instead of doing... if (p && p->q && p->q->r) p->q->r->DoSomething(); ...having a succinct syntax by using some sort of short-circuiting smart pointer, or some other kind of syntax leveraging operator overloading, or something in the Standard C++ Library, or in Boost. p?->q?->r?->DoSomething(); // C++ pseudo-code. Context is C++17 in particular. The best you can do is collapse all the member accesses into one function. This assumes without checking that everything is a pointer: template <class C, class PM, class... PMs> auto

According to https://gcc.gnu.org/projects/cxx-status.html , version 7 of g++, used with flag -std=c++1z , supports template argument deduction for class templates. I would expect the following code to compile, especially as Base is an abstract class, therefore: 1. the compiler knows no instance of Base can be created; 2. the pointer to base pt_base points to a clearly defined instance (i.e. Derived<int>{42} ) where the type ( int ) is explicit. template<typename ValueType> class Base { public: virtual ValueType getValue() = 0; }; template<typename ValueType> class Derived : public Base

If I theoretically have a sequence of integers like std::integer_sequence<int, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9> How can I filter it with some compile-time predicate to get a potentially smaller std::integer_sequence<int, ...> ? For the sake of argument, let's say that I want only the even values, which leads to the question of "How can I make the following static_assert (or something close) pass?" static_assert(std::is_same_v<std::integer_sequence<int, 0, 2, 4, 6, 8>, decltype(FilterEvens(std::integer_sequence<int, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9>{}))>, "Integer sequences should be equal"); This

I am learning the new c++17 fold expression and I saw this code from c++17 fold expression . I would like to know why this code work : template<typename ...Args> void printer(Args&&... args) { (std::cout << ... << args) << '\n'; } but not this one : template<typename ...Args> void printer(Args&&... args) { (std::cout << args << ...) << '\n'; } which could seems logic too and would reverse the print order in my opinion. As seen on cppreference , binary folds can have the following two forms: Where E is the pack expression and I is the initialization expression . There is no binary fold that