作一个结构清晰OO，链接有点问题。

sybaselu

1. 
   
2. #include <stdio.h>
   
3. 
   
4. #define interface struct
   
5. 
   
6. using namespace std;
   
7. 
   
8. /*
   
9. * Interface of this pure class, all methods were called by the pure class.
   
10. */
    
11. interface IXMLReaderContext            
    
12. {
    
13. public:
    
14.       virtual void AddAttribute() const = 0;
    
15.       virtual void Display() const = 0;
    
16. };
    
17. 
    
18. class TVReader : public IXMLReaderContext
    
19. {
    
20. public:
    
21.       TVReader();
    
22.       ~TVReader();
    
23. 
    
24.       void AddAttribute() const;
    
25.       void Display() const  { printf(" Inside TVReader...\n"); }
    
26. }
    
27. class HeadendFileReader : public IXMLReaderContext
    
28. {
    
29. public:
    
30.       HeadendFileReader();
    
31.       ~HeadendFileReader();
    
32. 
    
33.       void AddAttribute() const;
    
34.       void Display() const  { printf("Inside HeadendFileReader...\n"); }
    
35. };
    
36. class RegistryReader : public IXMLReaderContext
    
37. {
    
38. public:
    
39.       RegistryReader();
    
40.       ~RegistryReader();
    
41. 
    
42.       void AddAttribute() const;
    
43.       void Display() const  { printf("Inside RegistryReader...\n"); }
    
44. };
    
45. 
    
46. 
    
47. static void DisplayObject(IXMLReaderContext& Context);
    
48. 
    
49. int main()
    
50. {
    
51.     TVReader                  tvreader;
    
52.     HeadendFileReader  headendreader;
    
53.     RegistryReader        registryreader;
    
54. 
    
55.     DisplayObject(tvreader);
    
56.     DisplayObject(headendreader);
    
57.     DisplayObject(registryreader);
    
58. 
    
59.     return 0;
    
60. }
    
61. 
    
62. static void DisplayObject(IXMLReaderContext& Context)
    
63. {
    
64.     Context.Display();
    
65. }
    
66. 
    

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编译正常，链接有问题

1. 
   
2. [root@root Parser]# g++ -c virtual.cpp -o virtual.o
   
3. [root@root Parser]# g++ -o virtual virtual.o
   
4. virtual.o(.text+0x19): In function `TVReader::TVReader()':
   
5. : undefined reference to `vtable for TVReader'
   
6. virtual.o(.text+0x39): In function `TVReader::TVReader()':
   
7. : undefined reference to `vtable for TVReader'
   
8. virtual.o(.text+0x48): In function `TVReader::~TVReader()':
   
9. : undefined reference to `vtable for TVReader'
   
10. virtual.o(.text+0x56): In function `TVReader::~TVReader()':
    
11. : undefined reference to `vtable for TVReader'
    
12. collect2: ld returned 1 exit status
    
13. [root@root Parser]#
    

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MatthewGong

好像构造与解析函数， AddAttribute函数 都只有声明而没有实现？

2. #include <stdio.h>
4. #define interface struct
6. using namespace std;
8. /*
9. * Interface of this pure class, all methods were called by the pure class.
10. */
11. interface IXMLReaderContext            
12. {
13. public:
14.       IXMLReaderContext(){}
15.       virtual ~IXMLReaderContext(){}
16.       virtual void AddAttribute() const = 0;
17.       virtual void Display() const = 0;
18. };
20. class TVReader : public IXMLReaderContext
21. {
22. public:
23.       TVReader(){}
24.       ~TVReader(){}
26.       void AddAttribute() const{}
27.       void Display() const  { printf(" Inside TVReader...\n"); }
28. };
30. class HeadendFileReader : public IXMLReaderContext
31. {
32. public:
33.       HeadendFileReader(){}
34.       ~HeadendFileReader(){}
36.       void AddAttribute() const{}
37.       void Display() const  { printf("Inside HeadendFileReader...\n"); }
38. };
39. class RegistryReader : public IXMLReaderContext
40. {
41. public:
42.       RegistryReader(){}
43.       ~RegistryReader(){}
45.       void AddAttribute() const{}
46.       void Display() const  { printf("Inside RegistryReader...\n"); }
47. };
50. static void DisplayObject(IXMLReaderContext& Context);
52. int main()
53. {
54.     TVReader                  tvreader;
55.     HeadendFileReader  headendreader;
56.     RegistryReader        registryreader;
58.     DisplayObject(tvreader);
59.     DisplayObject(headendreader);
60.     DisplayObject(registryreader);
62.     return 0;
63. }
65. static void DisplayObject(IXMLReaderContext& Context)
66. {
67.     Context.Display();
68. }

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