error C2679: binary '>>' : no operator found-CodePudding

The full error message reads:

Error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'Ar<int>' (or there is no acceptable conversion)

How can I fix it?

#include <iostream>

using namespace std;

template<class T>
class Dun
{
private:
    T* array{ nullptr };

public:
    Dun(T* _array) : array(_array) {}

    T& Get(int index)
    {
        return this->array[index];
    }
};

template<class T>
class Ar
{
private:
    Dun<T>* data{nullptr};

public:
    Ar(Dun<T>* _data) : data(_data) {}

    T& operator[] (int index)
    {
        return this->data->Get(index);
    }
};

int main()
{
    int a[4] = { 1, 2, 3, 4 };

    auto ar = new Dun<int>(a);
    auto ur = new Ar<int>(ar);

    cout << ur[1];

    return 0;
}

CodePudding user response：

You don't need pointers here

int main()
{
    int a[4] = { 1, 2, 3, 4 };

    Dun<int> ar{a};
    Ar<int> ur{&ar};

    cout << ur[1];

    return 0;
}

otherwise you'd have to dereference your pointer before your operator[] can be used

cout << (*ur)[1];