// MS C++ 2013
template<class _Fty> class function;
template<class _Fty> class function : public _Get_function_impl<_Fty>::type { ... }// GCC 4.8.2
template<typename _Signature>                  class function;
template<typename _Res, typename... _ArgTypes> class function<_Res(_ArgTypes...)>: public _Maybe_unary_or_binary_function<_Res, _ArgTypes...>, private _Function_base { ... }

// cplusplus.comtemplate <class T> function;     // undefined
template <class Ret, class... Args> class function<Ret(Args...)>;

#include <iostream>
#include <functional>
using namespace std;int g_Minus(int i, int j)
{return i - j;
}int main()
{function<int(int, int)> f = g_Minus;cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;template <class T>
T g_Minus(T i, T j)
{return i - j;
}int main()
{function<int(int, int)> f = g_Minus<int>;cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;auto g_Minus = [](int i, int j){ return i - j; };int main()
{function<int(int, int)> f = g_Minus;cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;struct Minus
{int operator() (int i, int j){return i - j;}
};int main()
{function<int(int, int)> f = Minus();cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;template <class T>
struct Minus
{ T operator() (T i, T j){return i - j;}
};int main()
{function<int(int, int)> f = Minus<int>();cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;class Math
{
public:static int Minus(int i, int j){return i - j;}
};int main()
{function<int(int, int)> f = &Math::Minus;cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;class Math
{
public:template <class T>static T Minus(T i, T j){return i - j;}
};int main()
{function<int(int, int)> f = &Math::Minus<int>;cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;class Math
{
public:int Minus(int i, int j){return i - j;}
};int main()
{Math m;function<int(int, int)> f = bind(&Math::Minus, &m, placeholders::_1, placeholders::_2);cout << f(1, 2) << endl;                                            // -1return 1;
}

#include <iostream>
#include <functional>
using namespace std;class Math
{
public:template <class T>T Minus(T i, T j){return i - j;}
};int main()
{Math m;function<int(int, int)> f = bind(&Math::Minus<int>, &m, placeholders::_1, placeholders::_2);cout << f(1, 2) << endl;                                            // -1return 1;
}