Sams Teach Yourself C++ in 21 Days

37: return theStream;

38: }

39:

40: istream& operator>>( istream& theStream,String& theString)

41: {

42: theStream >> theString.GetString();

43: return theStream;

44: }

45:

46: int main()

47: {

48: String theString(“Hello world.”);

49: cout << theString;

50: return 0;

51: }

5. You can’t put the frienddeclaration into the function. You must declare the func-
   tion to be a friend in the class.


6. The following is the fixed listing:
   0: Bug Busters
   1: #include
   2: using namespace std;
   3: class Animal;
   4:
   5: void setValue(Animal& , int);
   6:
   7: class Animal
   8: {
   9: public:
   10: friend void setValue(Animal&, int);
   11: int GetWeight()const { return itsWeight; }
   12: int GetAge() const { return itsAge; }
   13: private:
   14: int itsWeight;
   15: int itsAge;
   16: };
   17:
   18: void setValue(Animal& theAnimal, int theWeight)
   19: {
   20: theAnimal.itsWeight = theWeight;
   21: }
   22:
   23: int main()
   24: {
   25: Animal peppy;
   26: setValue(peppy,5);
   27: return 0;
   28: }

858 Appendix D

32 0672327112_app_d.qxd 11/19/04 12:30 PM Page 858