Is it possible to have an "auto" member variable?

auto, c++, struct

Solution

You can, but you have to declare it `static` and `const`:

struct Timer {
    static const auto start = 0;
};

A working example in Coliru.

With this limitation, you therefore cannot have `start` as a non-static member, and cannot have different values in different objects.

If you want different types of `start` for different objects, better have your class as a template

template<typename T>
struct Timer {
    T start;
};

If you want to deduce the type of `T`, you can make a factory-like function that does the type deduction.

template<typename T>
Timer<typename std::decay<T>::type> MakeTimer(T&& startVal) {   // Forwards the parameter
   return Timer<typename std::decay<T>::type>{std::forward<T>(startVal)};
}

Live example.

Problem

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's giving me this error: Cannot deduce auto type. Initializer required Is there a way around it? ``` struct Timer { auto start; }; ```

Original source

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