Sams Teach Yourself C++ in 21 Days

Handling Errors and Exceptions 739

20

It is tedious and error-prone to have each of these catchstatements individually print the

appropriate message. This job belongs to the object, which knows what type of object it

is and what value it received. Listing 20.8 takes a more object-oriented approach to this

problem, using virtual functions so that each exception “does the right thing.”

LISTING20.8 Passing by Reference and Using Virtual Functions in Exceptions

0: #include <iostream>

1: using namespace std;

2:

3: const int DefaultSize = 10;

4:

5: class Array

6: {

7: public:

8: // constructors

9: Array(int itsSize = DefaultSize);

10: Array(const Array &rhs);

11: ~Array() { delete [] pType;}

12:

13: // operators

14: Array& operator=(const Array&);

15: int& operator[](int offSet);

16: const int& operator[](int offSet) const;

17:

18: // accessors

19: int GetitsSize() const { return itsSize; }

20:

21: // friend function

22: friend ostream& operator<<

23: (ostream&, const Array&);

24:

25: // define the exception classes

26: class xBoundary {};

27: class xSize

28: {

29: public:

30: xSize(int size):itsSize(size) {}

31: ~xSize(){}

32: virtual int GetSize() { return itsSize; }

33: virtual void PrintError()

34: {

35: cout << “Size error. Received: “;

36: cout << itsSize << endl;

37: }

38: protected:

39: int itsSize;

40: };

41: