// greater.cpp - demonstrates a function template
// cmc, 11/22/2010

#include <iostream>
using std::cout;
using std::endl;
using std::ostream;

// greater(x, y) - returns reference to greater of x or y
//                 assumption: operator> is defined for type T
template <typename T>
T const &greater(T const &x, T const &y) {
    return (x > y) ? x : y;
}

class Double { // simple wrapper class to test greater for user-defined type
public:
    friend bool operator> (Double const x, Double const y)
    {   return x.value > y.value;  }
    friend ostream &operator<< (ostream &out, Double const &d)
    {   return out << d.value;  }
    Double(double d = 0) : value(d) { }
private:
    double value;
};

int main() {
    
    // let compiler deduce a couple of primitive types
    cout << greater(1, 2) << endl;            // T is int
    cout << greater('a', 'A') << endl;        // T is char

    // let compiler deduce a user-defined type - T is Double
    cout << greater(Double(5.62), Double(3.48)) << endl;

    // mix types by telling the compiler how to convert them
    cout << greater<char>(17, 'A') << endl;     // T is char
    cout << greater<int> (17, 'A') << endl;     // T is int
    cout << greater<int>('a', 'A') << endl;     // T is int
}