template and operator overloading and iterator

Question

I am asked to write an iterator with the same function as istream_iterator, and the iterator's name is CMyistream_iterator. I want to set up the function of * operator as it is used in iterators.

  template<class T>
    class CMyistream_iterator{
        public:
        T my;
        T* cm;
        CMyistream_iterator(istream& x):my(x){};
        T operator * (CMyistream_iterator<T>& p);
    };
    template<class T>
    T CMyistream_iterator<T>::operator * (CMyistream_iterator<T>& p){return p.my;}
    int main()
    {
        CMyistream_iterator<int> inputInt(cin);
        int n1,n2,n3;
        n1 = * inputInt;
    }

But the code goes wrong and saying that" no match for 'operator*'(operand type is CMyistream)". Could anyone help me?

Answer 1

You problem is not related to templates, but to basics of operator overloading. You need to write simply

T operator * ();

and

T CMyistream_iterator<T>::operator * (){
    return my; // meaning this->my
}

The reason is that as your operators are already class members, they already have one implicit parameter — the class object itself, and this is the parameter you need to use.

The code as you wrote it declares not indirection operator ( *x ) , but multiplication operator ( x*y ).

Another problem in your code is that you are trying to convert istream to int in CMyistream_iterator(istream& x):my(x){}; , but that's unrelated to the compilation error you mentioned; and the solution of this problem depends on what exactly you need to do.