Sams Teach Yourself C++ in 21 Days

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

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

14:

15: private:

16: int itsVal;

17: };

18:

19: Counter::Counter():

20: itsVal(0)

21: {}

22:

23: int main()

24: {

25: Counter i;

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

27: i.Increment();

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

29: return 0;

30: }

The value of i is 0

The value of i is 1

Listing 10.7 adds an Incrementfunction, defined on line 13. Although this

works, it is cumbersome to use. The program cries out for the capability to add a

++operator, and, of course, this can be done.

Overloading the Prefix Operator ....................................................................

Prefix operators can be overloaded by declaring functions with the form:

returnTypeoperator op ()

Here,opis the operator to overload. Thus, the ++operator can be overloaded with the

following syntax:

void operator++ ()

This statement indicates that you are overloading the ++operator and that it will not

result in a return value—thus voidis the return type. Listing 10.8 demonstrates this alter-

native.

LISTING10.8 Overloadingoperator++

1: // Listing 10.8 - The Counter class

2: // prefix increment operator

3:

OUTPUT

304 Day 10

LISTING10.7 continued

ANALYSIS