Create a new class called Calculator.  A calculator should be able to add, subtract, multiply, divide and clear.  Test your calculator by writing a main program incorporating the test code below:

Calculator mycalc;
mycalc.clear();
mycalc.add(4.52);
mycalc.add(3.789);
mycalc.divide(2.6);
mycalc.multiply(3.12);
mycalc.subtract(2.678);
cout << mycalc.display() << endl;       // prints out "7.2928"
mycalc.clear();
mycalc.add(5.0);
cout << mycalc.display() << endl;       // prints out "5"

//advanced stuff #1: add a constructor

Calculator calc1;

cout << calc1.display() << endl; //prints out 0

//advanced stuff #2: add a parameterized constructor

Calculator calc2(5);

cout << calc2.display() << endl; //prints out 5

//advanced stuff #3: (10 points extra credit) Define calculator addition (overload the '+' operator)

Calculator calc3(7);

calc1 = calc2 + calc3;

cout << calc1.display() << endl; //prints out 12

//advanced stuff #4 (10 points extra credit): Create an 'undo' method for the calculator

mycalc.undo();

mycalc.undo();

cout << mycalc.display()<< endl; //prints out 7.2928

//advanced stuff #5 (10 points extra credit): Create a 'redo' method for the calculator

mycalc.redo();

mycalc.redo();

cout << mycalc.display()<< endl; //prints out 5