Creating template function overloads for pointer and non pointer type data held inside a container

Question

I am trying to create a template function that is overloaded for pointer and non pointers. I did this and it works.

    template<class D, class V>
    bool Same(D d, V v){ return d == v; }

    template<class D, class V>
    bool Same(D* d, V v) { return *d==v;}

Now I want to extend it such that a templated container is a paramater and there must be one version for the container with pointer and other with the container for non pointers. I am not able to figure it out. I tried this but it won't work.

    template< template<class> class Container, class Data, class Value>
    bool func(Container<Data> &c, Value v)
    {
        return c[0] == v;
    }

    template< template<class> class Container, class Data, class Value>
    bool func(Container<Data*> &c, Value v)
    {
            return *c[0] == v;
    }

The error c2040 says int* differs in level of indirection from int and points to the first function.

How can I get it to work?

Rest of thecode

template<class D>
class Vec
{
    std::vector<D> m_vec;
public:
    void push_back(D d) { m_vec.push_back(d); }
        D operator[](int i) { return m_vec[i]; }
};
void test_template()
{
    Same<int, int>(2,3);
    Info i = {4};
    Same<Info, int>(i, 2);
    Info ii = {2 };
    Info *pi = &ii;
    Same<Info, int>(pi, 2);

    Vec<int> iv;
    iv.push_back(3);
    func<Vec, int, int>(iv, 3);
    Vec<int*> pv;
    pv.push_back(new int(3));
    func<Vec, int*, int>(pv, 3);
}

Drew McGowen · Accepted Answer · 2013-07-24 20:17:01Z

3

For the second call to func, the second template parameter should just be int, not int *. Otherwise, the second func declaratino will look for a Vec<int **> as the first template argument (since it has its own pointer).

func<Vec, int, int>(pv, 3);

EDIT: as DyP mentioned, you can also leave out the template arguments completely, as the compiler should be able to deduce them from the actual function arguments.

edited Jul 24, 2013 at 20:17

answered Jul 24, 2013 at 20:08

Drew McGowen

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