difference between A aaa; and A aaa();

Question

class A{
    private:
        string a;
    public:
        A():a("hello world"){};
        A(const string & arg):a(arg){};
        void put()const{cout<<a;};
};

A aaa();
A bbb;

So what's the difference between A aaa(); and A bbb; Is aaa a function?

Answer 1

Yes, the first one is interpreted as a function declaration. It's been called the Most Vexing Parse.