Question

#include <iostream>
using namespace std;

class B
{
public:
  int getMsg(int i)
  {
    return i + 1;
  }
};

class A
{
  B b;
public:
  void run()
  {
    taunt(b.getMsg);
  }

  void taunt(int (*msg)(int))
  {
    cout << (*msg)(1) << endl;
  }
};

int main()
{
  A a;
  a.run();
}

The above code has a class B inside a class A, and class A has a method taunt that takes a function as an argument. class B’s getMsg is passed into taunt…The above code generated the following error message: “error: no matching function for call to ‘A::taunt()'”

What’s causing the error message in the above code? Am I missing something?

Update:

#include <iostream>
using namespace std;

class B
{
public:
  int getMsg(int i)
  {
    return i + 1;
  }
};

class A
{
  B b;
public:
  void run()
  {
    taunt(b.getMsg);
  }

  void taunt(int (B::*msg)(int))
  {
    cout << (*msg)(1) << endl;
  }
};

int main()
{
  A a;
  a.run();
}

t.cpp: In member function ‘void A::run()’:
Line 19: error: no matching function for call to ‘A::taunt()’
compilation terminated due to -Wfatal-errors.

I’m still getting the same error after changing (*msg)(int) to (B::*msg)(int)

Answer 1

b.getMsg is not the correct way to form a pointer to member, you need &B::getMsg.

(*msg)(1) is not the correct way to call a function through a pointer to member you need to specify an object to call the function on, e.g. (using a temporary) (B().*msg)(1).