#include <iostream>
using namespace std;

int do_it(int x, int y, int (*func)(int,int))
{
  return func(x,y);
}

int add(int x, int y)
{
  return x + y;
}

int subt(int x, int y)
{
  return x - y;
}

int mult(int x, int y)
{
  return x * y;
}

int main()
{
  int a, b, c = 1;
  while(c!=0)
  {
    cout << "Hello. Would you like to\n0)Quit\n1) Add\n2) Subtract or\n3) Multiply\ntoday?" << endl;
    cin >> c;
    cout << "Give me a and b please" << endl;
    cin >> a >> b;
    if(c==1)
      cout << a << " + " << b << " = " << do_it(a,b,add);
    if(c==2)
      cout << a << " - " << b << " = " << do_it(a,b,subt);
    if(c==3)
      cout << a << " * " << b << " = " << do_it(a,b,mult);
    cout << endl << endl;
  }
  cout << "Au revoir!" << endl; 
  return 0;
}

#include <iostream>
#include <functional>

using namespace std;

template <typename T, typename F>
T do_it(T x, T y, F func)
{
  return func(x, y);
}

int main()
{
  int a, b, c = 1;
 
  while (c != 0)
  {
    cout << "Hello. Would you like to"<< endl
         << "0)Quit" << endl
         << "1) Add" << endl
         << "2) Subtract or" << endl
         << "3) Multiply" << endl
         << "today?" << endl;
         
    cin >> c;
   
    cout << "Give me a and b please" << endl;
   
    cin >> a >> b;
   
    switch (c)
    {
      case 1:
        cout << a << " + " << b << " = " << do_it(a, b, plus<int>());
        break;
      case 2:
        cout << a << " - " << b << " = " << do_it(a, b, minus<int>());
        break;
      case 3:
        cout << a << " * " << b << " = " << do_it(a, b, multiplies<int>());
        break;
    }
   
    cout << endl << endl;
  }
 
  cout << "Au revoir!" << endl;
 
  return 0;
}