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Asked: 2026-06-09T19:12:56+00:00

Is casting the const ness of member function pointers defined in C++? Is the

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Is casting the constness of member function pointers defined in C++? Is the following valid code?

struct T {
  void foo(int i) const { std::cout << i << std::endl;};
};

void (T::*f1)(int) const = &T::foo;
void (T::*f2)(int)       = reinterpret_cast<void (T::*)(int)>(f1);
T t;
(t.*f2)(1);

Update:

The reason why I need this is that I’m writing a function that accepts both an object and a member function pointer to that object. I need a version for const objects (accepting only const functions) and a normal one. Since I don’t want duplicate code, my idea was to put the actual code in the non-const version and call it from the const one, casting away any consts.

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1 Answer

  1. Editorial Team

    Compiler eats it.
    But the backward cast is more useful.

    And again but – it is better to don’t use it, const_cast is usually just a quick and dirty solution, which you apply only when there are not any other solution.

    Answer to update

    If I understand you correctly you are going to use one object and two function. First function accepts const object and const member-function, second – non-const object and non-const member-function.

    According to given information you can change second function to accept non-const object and const member-function. And give them one non-const object and its const member-function.

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