Sams Teach Yourself C++ in 21 Days

When the Cats fall out of scope, their destructors are automatically invoked. The imple-

mentation of the Catdestructor is shown on lines 37–43. deleteis called on both point-

ers,itsAgeand itsWeight, returning the allocated memory to the free store. Also, for

safety, the pointers are reassigned to a null value.

Operator Overloading ..........................................................................................

C++ has a number of built-in types, including int,float,char, and so forth. Each of

these has a number of built-in operators, such as addition (+) and multiplication (*). C++

enables you to add these operators to your own classes as well.

To explore operator overloading fully, Listing 10.6 creates a new class,Counter. A

Counterobject will be used in counting (surprise!) in loops and other applications in

which a number must be incremented, decremented, or otherwise tracked.

LISTING10.6 The CounterClass

1: // Listing 10.6 - The Counter class

2:

3: #include <iostream>

4: using namespace std;

5:

6: class Counter

7: {

8: public:

9: Counter();

10: ~Counter(){}

11: int GetItsVal()const { return itsVal; }

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

13:

14: private:

302 Day 10

FIGURE10.3

Deep copy illustrated.^5

5

itsAge

old CAT

itsAge

New CAT

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