Слабо понимаю что ему нужно. (пример из википедии)

автор#include <iostream>
#include <functional>

struct A {
A(int num) : num_(num){}
void printNumberLetter(char c) const { std::cout << "Number: " << num_ << " Letter: " << c << std::endl; }
int num_;
};

int main()
{
// Содержит вызов метода класса.
std::function<void(const A&, char)> f_printA = &A::printNumberLetter;
A a(10);
f_printA(a, 'A');

}


Сообщения от компилятора:

автор1>------ Build started: Project: Project1, Configuration: Debug Win32 ------
1> main.cpp
1>c:\program files (x86)\microsoft visual studio 12.0\vc\include\functional(506): error C2664: 'void std::_Func_class<_Ret,const A &,char>::_Set(std::_Func_base<_Ret,const A &,char> *)' : cannot convert argument 1 from '_Myimpl *' to 'std::_Func_base<_Ret,const A &,char> *'
1> with
1> [
1> _Ret=void
1> ]
1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\functional(442) : see reference to function template instantiation 'void std::_Func_class<_Ret,const A &,char>::_Do_alloc<_Myimpl,_Fret(__thiscall A::* const &)(char) const,_Alloc>(_Fty,_Alloc)' being compiled
1> with
1> [
1> _Ret=void
1> , _Fret=void
1> , _Alloc=std::allocator<std::_Func_class<void,const A &,char>>
1> , _Fty=void (__thiscall A::* const &)(char) const
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\functional(442) : see reference to function template instantiation 'void std::_Func_class<_Ret,const A &,char>::_Do_alloc<_Myimpl,_Fret(__thiscall A::* const &)(char) const,_Alloc>(_Fty,_Alloc)' being compiled
1> with
1> [
1> _Ret=void
1> , _Fret=void
1> , _Alloc=std::allocator<std::_Func_class<void,const A &,char>>
1> , _Fty=void (__thiscall A::* const &)(char) const
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\functional(442) : see reference to function template instantiation 'void std::_Func_class<_Ret,const A &,char>::_Reset_alloc<_Fret,A,char,std::allocator<std::_Func_class<_Ret,const A &,char>>>(_Fret (__thiscall A::* const )(char) const,_Alloc)' being compiled
1> with
1> [
1> _Ret=void
1> , _Fret=void
1> , _Alloc=std::allocator<std::_Func_class<void,const A &,char>>
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\functional(442) : see reference to function template instantiation 'void std::_Func_class<_Ret,const A &,char>::_Reset_alloc<_Fret,A,char,std::allocator<std::_Func_class<_Ret,const A &,char>>>(_Fret (__thiscall A::* const )(char) const,_Alloc)' being compiled
1> with
1> [
1> _Ret=void
1> , _Fret=void
1> , _Alloc=std::allocator<std::_Func_class<void,const A &,char>>
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\functional(671) : see reference to function template instantiation 'void std::_Func_class<_Ret,const A &,char>::_Reset<void,A,char>(_Fret (__thiscall A::* const )(char) const)' being compiled
1> with
1> [
1> _Ret=void
1> , _Fret=void
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\functional(671) : see reference to function template instantiation 'void std::_Func_class<_Ret,const A &,char>::_Reset<void,A,char>(_Fret (__thiscall A::* const )(char) const)' being compiled
1> with
1> [
1> _Ret=void
1> , _Fret=void
1> ]
1> c:\users\admin\documents\visual studio 2013\projects\project1\main.cpp(13) : see reference to function template instantiation 'std::function<void (const A &,char)>::function<void(__thiscall A::* )(char) const>(_Fx &&)' being compiled
1> with
1> [
1> _Fx=void (__thiscall A::* )(char) const
1> ]
1> c:\users\admin\documents\visual studio 2013\projects\project1\main.cpp(13) : see reference to function template instantiation 'std::function<void (const A &,char)>::function<void(__thiscall A::* )(char) const>(_Fx &&)' being compiled
1> with
1> [
1> _Fx=void (__thiscall A::* )(char) const
1> ]
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========