Sams Teach Yourself C++ in 21 Days

Understanding Pointers 239

25: cout << “Destructor called. “ << endl;^8

26: }

27:

28: int main()

29: {

30: cout << “SimpleCat Frisky... “ << endl;

31: SimpleCat Frisky;

32: cout << “SimpleCat *pRags = new SimpleCat...” << endl;

33: SimpleCat * pRags = new SimpleCat;

34: cout << “delete pRags... “ << endl;

35: delete pRags;

36: cout << “Exiting, watch Frisky go... “ << endl;

37: return 0;

38: }

SimpleCat Frisky...

Constructor called.

SimpleCat *pRags = new SimpleCat..

Constructor called.

delete pRags...

Destructor called.

Exiting, watch Frisky go...

Destructor called.

Lines 8–15 declare the stripped-down class SimpleCat. Line 11 declares

SimpleCat’s constructor, and lines 17–21 contain its definition. Line 12 declares

SimpleCat’s destructor, and lines 23–26 contain its definition. As you can see, both the

constructor and destructor simply print a simple message to let you know they have been

called.

On line 31,Friskyis created as a regular local variable, thus it is created on the stack.

This creation causes the constructor to be called. On line 33, the SimpleCatpointed to

by pRagsis also created; however, because a pointer is being used, it is created on the

heap. Once again, the constructor is called.

On line 35,deleteis called on the pointer,pRags. This causes the destructor to be called

and the memory that had been allocated to hold this SimpleCatobject to be returned.

When the function ends on line 38,Friskygoes out of scope, and its destructor is called.

Accessing Data Members ....................................................................................

You learned on Day 6, “Understanding Object-Oriented Programming,” that you

accessed data members and functions by using the dot (.) operator. As you should be

aware, this works for Catobjects created locally.

OUTPUT

LISTING8.5 continued

ANALYSIS