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<H2 ALIGN="CENTER"><BR>
<A NAME="Heading1"></A><FONT COLOR="#000077">In Review</FONT></H2>
<P>The Week in Review program for Week 2 brings together many of the skills you've
acquired over the past fortnight and produces a powerful program.</P>
<P>This demonstration of linked lists utilizes virtual functions, pure virtual functions,
function overriding, polymorphism, public inheritance, function overloading, forever
loops, pointers, references, and more.</P>
<P>The goal of this program is to create a linked list. The nodes on the list are
designed to hold parts, as might be used in a factory. While this is not the final
form of this program, it does make a good demonstration of a fairly advanced data
structure. The code list is 311 lines. Try to analyze the code on your own before
reading the analysis that follows the output.</P>
<P><A NAME="Heading2"></A><FONT SIZE="4" COLOR="#000077"><B>Listing R2.1. Week 2
in Review listing.</B></FONT>
<PRE><FONT COLOR="#0066FF">0: // **************************************************
1: //
2: // Title: Week 2 in Review
3: //
4: // File: Week2
5: //
6: // Description: Provide a linked list demonstration program
7: //
8: // Classes: PART - holds part numbers and potentially other
9: // information about parts
10: //
11: // PartNode - acts as a node in a PartsList
12: //
13: // PartsList - provides the mechanisms for a linked list Âof parts
14: //
15: // Author: Jesse Liberty (jl)
16: //
17: // Developed: 486/66 32mb RAM MVC 1.5
18: //
19: // Target: Platform independent
20: //
21: // Rev History: 9/94 - First release (jl)
22: //
23: // **************************************************
24:
25: #include <iostream.h>
26:
27: typedef unsigned long ULONG;
28: typedef unsigned short USHORT;
29:
30:
31: // **************** Part ************
32:
33: // Abstract base class of parts
34: class Part
35: {
36: public:
37: Part():itsPartNumber(1) {}
38: Part(ULONG PartNumber):itsPartNumber(PartNumber){}
39: virtual ~Part(){};
40: ULONG GetPartNumber() const { return itsPartNumber; }
41: virtual void Display() const =0; // must be overridden
42: private:
43: ULONG itsPartNumber;
44: };
45:
46: // implementation of pure virtual function so that
47: // derived classes can chain up
48: void Part::Display() const
49: {
50: cout << "\nPart Number: " << itsPartNumber << endl;
51: }
52:
53: // **************** Car Part ************
54:
55: class CarPart : public Part
56: {
57: public:
58: CarPart():itsModelYear(94){}
59: CarPart(USHORT year, ULONG partNumber);
60: virtual void Display() const
61: {
62: Part::Display(); cout << "Model Year: ";
63: cout << itsModelYear << endl;
64: }
65: private:
66: USHORT itsModelYear;
67: };
68:
69: CarPart::CarPart(USHORT year, ULONG partNumber):
70: itsModelYear(year),
71: Part(partNumber)
72: {}
73:
74:
75: // **************** AirPlane Part ************
76:
77: class AirPlanePart : public Part
78: {
79: public:
80: AirPlanePart():itsEngineNumber(1){};
81: AirPlanePart(USHORT EngineNumber, ULONG PartNumber);
82: virtual void Display() const
83: {
84: Part::Display(); cout << "Engine No.: ";
85: cout << itsEngineNumber << endl;
86: }
87: private:
88: USHORT itsEngineNumber;
89: };
90:
91: AirPlanePart::AirPlanePart(USHORT EngineNumber, ULONG PartNumber):
92: itsEngineNumber(EngineNumber),
93: Part(PartNumber)
94: {}
95:
96: // **************** Part Node ************
97: class PartNode
98: {
99: public:
100: PartNode (Part*);
101: ~PartNode();
102: void SetNext(PartNode * node) { itsNext = node; }
103: PartNode * GetNext() const;
104: Part * GetPart() const;
105: private:
106: Part *itsPart;
107: PartNode * itsNext;
108: };
109:
110: // PartNode Implementations...
111:
112: PartNode::PartNode(Part* pPart):
113: itsPart(pPart),
114: itsNext(0)
115: {}
116:
117: PartNode::~PartNode()
118: {
119: delete itsPart;
120: itsPart = 0;
121: delete itsNext;
122: itsNext = 0;
123: }
124:
125: // Returns NULL if no next PartNode
126: PartNode * PartNode::GetNext() const
127: {
128: return itsNext;
129: }
130:
131: Part * PartNode::GetPart() const
132: {
133: if (itsPart)
134: return itsPart;
135: else
136: return NULL; //error
137: }
138:
139: // **************** Part List ************
140: class PartsList
141: {
142: public:
143: PartsList();
144: ~PartsList();
145: // needs copy constructor and operator equals!
146: Part* Find(ULONG & position, ULONG PartNumber) const;
147: ULONG GetCount() const { return itsCount; }
148: Part* GetFirst() const;
149: static PartsList& GetGlobalPartsList()
150: {
151: return GlobalPartsList;
152: }
153: void Insert(Part *);
154: void Iterate(void (Part::*f)()const) const;
155: Part* operator[](ULONG) const;
156: private:
157: PartNode * pHead;
158: ULONG itsCount;
159: static PartsList GlobalPartsList;
160: };
161:
162: PartsList PartsList::GlobalPartsList;
163:
164: // Implementations for Lists...
165:
166: PartsList::PartsList():
167: pHead(0),
168: itsCount(0)
169: {}
170:
171: PartsList::~PartsList()
172: {
173: delete pHead;
174: }
175:
176: Part* PartsList::GetFirst() const
177: {
178: if (pHead)
179: return pHead->GetPart();
180: else
181: return NULL; // error catch here
182: }
183:
184: Part * PartsList::operator[](ULONG offSet) const
185: {
186: PartNode* pNode = pHead;
187:
188: if (!pHead)
189: return NULL; // error catch here
190:
191: if (offSet > itsCount)
192: return NULL; // error
193:
194: for (ULONG i=0;i<offSet; i++)
195: pNode = pNode->GetNext();
196:
197: return pNode->GetPart();
198: }
199:
200: Part* PartsList::Find(ULONG & position, ULONG PartNumber) const
201: {
202: PartNode * pNode = 0;
203: for (pNode = pHead, position = 0;
204: pNode!=NULL;
205: pNode = pNode->GetNext(), position++)
206: {
207: if (pNode->GetPart()->GetPartNumber() == PartNumber)
208: break;
209: }
210: if (pNode == NULL)
211: return NULL;
212: else
213: return pNode->GetPart();
214: }
215:
216: void PartsList::Iterate(void (Part::*func)()const) const
217: {
218: if (!pHead)
219: return;
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