如果Template arg是函数指针

Question

If I have a template class

template <class T>
class foo
{  /**/  }

How will i find if T is a function pointer?

There is std::is_pointer and std::is_function but no is_function_pointer

Answer 1

Just remove the pointer and check if the result is a function.

Here is code sample:

#include <utility>
#include <iostream>


template<class T> constexpr bool foo() {
    using T2 = std::remove_pointer_t<T>;
    return std::is_function<T2>::value;
}


int main() {
    std::cout << "Is function? " << foo<void (int)>()
              << "; is function pointer? " << foo<int (*)()>() << "\n";

}