namespace std {

class string
{
private:
    char *_M_string;
    size_t _M_size;
    // as you can see, std::string is basically just a wrapper
    // around char * and size

public:
    // this constructs an empty string
    string()
        : _M_string(nullptr), _M_size(0) { }

    // this will actually copy the string, so it's not interesting to us...
    string(const string &other);

    // this is the constructor that will be called when you use std::move
    string(string &&other)
        : string() // <-- construct an empty string first
    {
        swap(_M_string, other._M_string);
        swap(_M_size, other._M_size);
        // and now "other" string is empty and "this" string has its content
    }

    ~string()
    {
        // deleting a nullptr is fine
        delete [] _M_string;
    }

    //... other stuff
};

} // std