// CS19 Fall 2005 Code example
// demonstration of Operator Overloading
// This is a modified version of displays 8.6 and 8.7 from
// Absolute C++, 2nd edition,  Walter Savitch, Addison Wesley

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

class intPair{
public:
    intPair(int f, int s){ first = f; second = s;}
    void setFirst(int n){ first = n;}
    void setSecond(int n){ second = n;}
    int getFirst( ) const{ return first;}
    int getSecond( ) const{ return second;}

    intPair operator++( ); //Prefix version
    intPair operator++(int); //Postfix version
    int& operator[](int index);
private:
    int first;
    int second;
};

// overload the post-increment operator
// int ignorMe is a marker only -- don't use it
intPair intPair::operator++(int ignoreMe){
    int fnum = first;
    int snum = second;
    first++;
    second++;
    return intPair(fnum, snum);
}

// overload the pre-increment operator
intPair intPair::operator++( ){
    first++;
    second++;
    return intPair(first, second);
}

//requires use of iostream and cstdlib:
int& intPair::operator[](int index){
    if (index == 1) return first;
    if (index == 2) return second;
    cerr << "Illegal index value in call to intPair::operator[]." << endl;
    exit(1);
}


// ------------------------------------------------------------

int main( ){
    intPair a(1,2);
    cout << "Postfix a++: Start value of object a: ";
    cout << a.getFirst( ) << " " << a.getSecond( ) << endl;
    intPair b = a++; 
    cout << "Value returned: ";
    cout << b.getFirst( ) << " " << b.getSecond( ) << endl;
    cout << "Changed object: ";
    cout << a.getFirst( ) << " " << a.getSecond( ) << endl;

// simple object so default memberwise copy works fine	
    a = intPair(1, 2); 
    cout << "Prefix ++a: Start value of object a: ";
    cout << a.getFirst( ) << " " << a.getSecond( ) << endl;
    intPair c = ++a;   
    cout << "Value returned: ";
    cout << c.getFirst( ) << " " << c.getSecond( ) << endl;
    cout << "Changed object: ";
    cout << a.getFirst( ) << " " << a.getSecond( ) << endl;

    a = intPair(1,2);
    cout << "Start value of object a: ";
    cout << a.getFirst( ) << " " << a.getSecond( ) << endl;
    cout << "operations:  a[1] = 5; a[2] = 7;" << endl;
    a[1] = 5; a[2] = 7;
     cout << "End value of object a: ";
    cout << a.getFirst( ) << " " << a.getSecond( ) << endl;

}