Is it possible to have an “auto” member variable?

Question

For example I wanted to have a variable of type auto because I\'m not sure what type it will be.

When I try to declare it in class/struct declaration it

Answer 1

Indirectly, provided that you don't reference a member of the class.

This can also now be achieved through deduction guides, these were introduced in C++17 and have recently (finally) support in VC++ has been added (clang and GCC already had it).

https://en.cppreference.com/w/cpp/language/class_template_argument_deduction

For example:

template 
struct CString;

template 
struct CString>
{
    std::array const Label;

    CString(std::array const & pInput) : Label(pInput) {}
};

template 
CString(std::array const & pInput) -> CString>;

https://godbolt.org/z/LyL7UW

This can be used to deduce class member types in a similar manner to auto. Although the member variables need to be Dependant somehow on the constructor arguments.