#include <iostream>
#include <string>
using namespace std;

template<class A, class B>
class my_pair{
public:
	A first;
	B second;
	my_pair(A x, B y):first(x), second(y){}
	void print();
};

template<class S>
void swapk(S &a, S &b){
   S t = a;
   a = b;
   b = t;
}

template<class S, class T>
my_pair<S,T> make_a_pair(S &a, T &b){
   return my_pair<S,T>(a,b);
}


void main(){
   int x=3, y=42;
   double p = 3.14159, e = 2.718;
   string s1 = "s1", s2 = "s2";
   swapk(x,y);
   cout << "after swap x y " << x << " " << y << endl;
   swapk(p,e);
   cout << "after swap p e " << p << " " << e << endl;
   swapk(s1,s2);
   cout << "after swap s1 s2 " << s1 << " " << s2 << endl;
   //swapk(s1, p); not allowed
   my_pair<string, double> pa = make_a_pair(s1, p);
   pa.print(); 
}

// show template scope resolution for method
// definition outside class
template<typename X, typename Y>
void my_pair<X,Y>::print(){
  cout << first << " " << second << endl;
}