Reading from a byte field by void* and reinterpret_cast

Question

I plan to read a type T from a byte field given by a void* the following way:

template <class T>
T read(void* ptr){
    return reinterpret_cast<T>(*ptr);
}

But I get some doubts: What does dereferencing a void* actually give into reinterpret_cast<T>? Just the byte at that position? Or 'magically' a byte sequence of the length of T? Should I first cast the void* into a T*?

Answer 1

You cannot dereference a void pointer, it does not point to an object. But the C standard dictatetes that:

A pointer to void may be converted to or from a pointer to any object type.

We can first convert ptr to a T* and then dereference it:

template <class T>
T read(void* ptr) {
    return *static_cast<T*>(ptr);
}