```#include <iostream>
#include "Rational.h"
using namespace std;

int main()
{
// Create and initialize two rational numbers r1 and r2.
Rational r1(4, 2);
Rational r2(2, 3);

// Test toString, add, subtract, multiply, and divide
cout << r1.toString() << " + " << r2.toString() << " = "
cout << r1.toString() << " - " << r2.toString() << " = "
<< r1.subtract(r2).toString() << endl;
cout << r1.toString() << " * " << r2.toString() << " = "
<< r1.multiply(r2).toString() << endl;
cout << r1.toString() << " / " << r2.toString() << " = "
<< r1.divide(r2).toString() << endl;

// Test intValue and double
cout << "r2.intValue()" << " is " << r2.intValue() << endl;
cout << "r2.doubleValue()" << " is " << r2.doubleValue() << endl;

// Test compareTo and equal
cout << "r1.compareTo(r2) is " << r1.compareTo(r2) << endl;
cout << "r2.compareTo(r1) is " << r2.compareTo(r1) << endl;
cout << "r1.compareTo(r1) is " << r1.compareTo(r1) << endl;
cout << "r1.equals(r1) is "
<< (r1.equals(r1) ? "true" : "false") << endl;
cout << "r1.equals(r2) is "
<< (r1.equals(r2) ? "true" : "false") << endl;

return 0;
}
```