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c++templatespointersc++11typename

Getting a typename given the typename of a pointer to it in C++

Consider the following code:

class c {
  //...
};

template <typename T>
void f(T k)
{
    auto item = new T;
    //...
}

We declare a class c and a template function f that creates a new object type T.

I want to change this function f so the template parameter can be a pointer type, it will be used as follows:

auto ptr = new c;
f<c*>(ptr);

Now, the problem comes when I try to create a new item auto item = new T;, because now T is now the typename of a pointer to c.

I know T will always be a pointer to something, how can I get the typename being pointed to by T? I want to do something like:

template <typename T>
void f(T k)
{
    // If T = int* -> Q = int
    typename ??????? Q;    // <<<<<<<<
    auto item = new Q;
    //...
}
Solution

  • With std::remove_pointer:

    #include <type_traits>

using Q = typename std::remove_pointer<T>::type;