// The template function compare, and a number of applications (most are OK, some lead to compile time errors).

#include <iostream>
#include <string>
#include "point.h"

class ComparsionProblem{};

template<typename T> int compare(const T &v1, const T &v2){
  if (v1 < v2) 
    return -1;
  else if (!(v1 < v2) && !(v2 < v1))  // better than v1 == v2
    return 0;
  else if (v2 < v1)                   // better than v1 > v2
    return 1;
  else 
    throw ComparsionProblem();
}

int main(){
  using namespace std;

  // Comparing int, infers the type automatically:
  cout << compare(1,2) << endl;             // -1
  cout << compare(1,1) << endl;             //  0
  cout << compare(2,1) << endl;             //  1
  cout << endl;

  // Passing type parameteter explicitly:
  cout << compare<int>(1,2) << endl;        // -1
  cout << compare<int>(1,1) << endl;        //  0
  cout << compare<int>(2,1) << endl;        //  1
  cout << endl;

  string s1 = "abe",
         s2 = "katten",
         s3 = "abe";

  // Comparing strings:
  cout << compare(s1,s2) << endl;           // -1
  cout << compare(s2,s1) << endl;           //  1
  cout << compare(s1,s3) << endl << endl;   //  0
  cout << endl;

  // Comparing C-style strings:
  cout << compare("ABE","KAT") << endl;     //  1. Wrong. Why? Because we compare pointers...
  cout << compare("KAT","ABE") << endl;     // -1. Wrong.
  cout << compare("kat","katten") << endl;  // error: no matching function for call to 
                                            // compare(const char [4], const char [7])

  // Comparing Points (without having defined < on Point):
  Point p1(1,2), p2(3,4);                   
  int i = compare(p1, p2);                  // error: no match for operator< in v2 < v1
                                            // error: no match for operator< in v1 < v2
                                            // error: no match for operator< in v2 < v1

}