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

class CharPair
{
public:
    CharPair( ){/*Body intentionally empty*/}
    CharPair(char firstValue, char secondValue)
                   : first(firstValue), second(secondValue)
    {/*Body intentionally empty*/}

    char& operator[](int index);
private:
    char first;
    char second;
};

int main( )
{
    CharPair a;
    a[1] = 'A';
    a[2] = 'B';
    cout << "a[1] and a[2] are:\n";
    cout << a[1] << a[2] << endl;

    cout << "Enter two letters (no spaces):\n";
    cin >> a[1] >> a[2];
    cout << "You entered:\n";
    cout << a[1] << a[2] << endl;

    return 0;
}

//Uses iostream and cstdlib:
char& CharPair::operator[](int index)
{
    if (index == 1)
        return first;
    else if (index == 2)
        return second;
    else
    {
        cout << "Illegal index value.\n";
        exit(1);
    }
}