Sams Teach Yourself C++ in 21 Days

Answers 865

D

5: // this line added to handle tail

6: if ( head == 0 ) tail = pt;

7:

8: head = pt;

9: theCount++;

10: }

11:

12: void List::append( int value )

13: {

14: ListCell *pt = new ListCell( value );

15: if ( head == 0 )

16: head = pt;

17: else

18: tail->next = pt;

19:

20: tail = pt;

21: theCount++;

22: }

23:

24: int List::is_present( int value ) const

25: {

26: if ( head == 0 ) return 0;

27: if ( head->val == value || tail->val == value )

28: return 1;

29:

30: ListCell *pt = head->next;

31: for (; pt != tail; pt = pt->next)

32: if ( pt->val == value )

33: return 1;

34:

35: return 0;

36: }

3. The following is one possible answer:
   0: // Exercise 19.3
   1: template
   2: List::~List()
   3: {
   4: ListCell pt = head;
   5:
   6: while ( pt )
   7: {
   8: ListCell tmp = pt;
   9: pt = pt->next;
   10: delete tmp;
   11: }
   12: head = tail = 0;
   13: }
   14:
   15: template

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