Sams Teach Yourself C++ in 21 Days

14: void SetItsVal(int x) {itsVal = x; }

15: void Increment() { ++itsVal; }

16: Counter operator++ ();

17:

18: private:

19: int itsVal;

20: };

21:

22: Counter::Counter():

23: itsVal(0)

24: {}

25:

26: Counter::Counter(int val):

27: itsVal(val)

28: {}

29:

30: Counter Counter::operator++()

31: {

32: ++itsVal;

33: return Counter (itsVal);

34: }

35:

36: int main()

37: {

38: Counter i;

39: cout << “The value of i is “ << i.GetItsVal() << endl;

40: i.Increment();

41: cout << “The value of i is “ << i.GetItsVal() << endl;

42: ++i;

43: cout << “The value of i is “ << i.GetItsVal() << endl;

44: Counter a = ++i;

45: cout << “The value of a: “ << a.GetItsVal();

46: cout << “ and i: “ << i.GetItsVal() << endl;

47: return 0;

48: }

The value of i is 0

The value of i is 1

The value of i is 2

The value of a: 3 and i: 3

On line 11, a new constructor is declared that takes an int. The implementation

is on lines 26–28. It initializes itsValwith the passed-in value.

The implementation of operator++is now simplified. On line 32,itsValis incre-

mented. Then on line 33, a temporary Counterobject is created, initialized to the value

in itsVal, and then returned as the result of the operator++.

OUTPUT

308 Day 10

LISTING10.10 continued

ANALYSIS