enum可以做索引

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mb5fdb0ff6b2aaf 2015-09-04 12:38:00

文章标签 i++ #include 封装快速索引虚函数 文章分类 代码人生

enum可以做索引

enum可以做索引，配上虚函数，或者函数指针，可以实现上层的统一封装和快速索引。

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MoTbl.cpp
#include <stdio.h>
#include <stdlib.h>
enum {
eA=0,
eB,
eC,
eD,
eMax
};
class Bs{
public:
virtual void say(){ printf("Bs\n"); }
};
class A: public Bs{
int aa[1];
public:
void say(){printf("A\n");}
void call(){printf("A::call\n");}
};
class B: public Bs{
int aa[3];
public:
void say(){printf("B\n");}
void sing(){printf("B::sing\n");}
};
class C: public Bs{
int aa[10];
public:
void say(){printf("C\n");}
};
class D: public Bs{
int aa[100];
public:
void say(){printf("D\n");}
};
class MoTbl{
public:
union{
struct{
A *a;
B *b;
C *c;
D *d;
}t;
void *tv[eMax];
};
};
int
main ( int argc, char *argv[] )
{
int i = 0;
MoTbl mt;
A a;
B b;
C c;
D d;
printf("A:%d\n",sizeof(MoTbl));
for(i=0; i<eMax; i++)
printf("%p\n",mt.tv[i]);
printf("--------------\n");
mt.tv[eA] = &a;
mt.tv[eB] = &b;
mt.tv[eC] = &c;
mt.tv[eD] = &d;
for(i=0; i<eMax; i++)
printf("%p\n",mt.tv[i]);
printf("--------------\n");
mt.t.a->say();
printf("--------------\n");
for(i=0; i<eMax; i++){
switch(i){enum 做索引 2012-10-11 18:17:14

分类： C/C++

enum可以做索引，配上虚函数，或者函数指针，可以实现上层的统一封装和快速索引。
点击(此处)折叠或打开
1. MoTbl.cpp
2. #include <stdio.h>
3. #include <stdlib.h>
5. enum {
6. eA=0,
7. eB,
8. eC,
9. eD,
10. eMax
11. };
13. class Bs{
14. public:
15. virtual void say(){ printf("Bs\n"); }
16. };
17. class A: public Bs{
18. int aa[1];
19. public:
20. void say(){printf("A\n");}
21. void call(){printf("A::call\n");}
23. };
24. class B: public Bs{
25. int aa[3];
26. public:
27. void say(){printf("B\n");}
28. void sing(){printf("B::sing\n");}
29. };
30. class C: public Bs{
31. int aa[10];
32. public:
33. void say(){printf("C\n");}
34. };
35. class D: public Bs{
36. int aa[100];
37. public:
38. void say(){printf("D\n");}
39. };
41. class MoTbl{
42. public:
43. union{
44. struct{
45. A *a;
46. B *b;
47. C *c;
48. D *d;
49. }t;
50. void *tv[eMax];
51. };
52. };
54. int
55. main ( int argc, char *argv[] )
56. {
57. int i = 0;
58. MoTbl mt;
60. A a;
61. B b;
62. C c;
63. D d;
65. printf("A:%d\n",sizeof(MoTbl));
67. for(i=0; i<eMax; i++)
68. printf("%p\n",mt.tv[i]);
69. printf("--------------\n");
71. mt.tv[eA] = &a;
72. mt.tv[eB] = &b;
73. mt.tv[eC] = &c;
74. mt.tv[eD] = &d;
76. for(i=0; i<eMax; i++)
77. printf("%p\n",mt.tv[i]);
78. printf("--------------\n");
80. mt.t.a->say();
81. printf("--------------\n");
83. for(i=0; i<eMax; i++){
84. switch(i){
85. case eA: mt.t.a->say(); break;
86. case eB: mt.t.b->say(); break;
87. case eC: mt.t.c->say(); break;
88. case eD: mt.t.d->say(); break;
89. }
90. }
91. printf("--------------\n");
93. for(i=0; i<eMax; i++)
94. ((Bs *)mt.tv[i])->say();
95. printf("--------------\n");
97. for(i=0; i<eMax; i++){
98. switch(i){
99. case eA: mt.t.a->call(); break;
100. case eB: mt.t.b->sing(); break;
101. }
103. }
104. printf("--------------\n");
106. }
输出
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1. A:16
2. 0xb7726ff4
3. 0xb77238e4
4. (nil)
5. 0xb7615ff4
6. --------------
7. 0xbff0cd98
8. 0xbff0cd88
9. 0xbff0cd5c
10. 0xbff0cbc8
11. --------------
12. A
13. --------------
14. A
15. B
16. C
17. D
18. --------------
19. A
20. B
21. C
22. D
23. --------------
24. A::call
25. B::sing
26. --------------
case eA: mt.t.a->say(); break;
case eB: mt.t.b->say(); break;
case eC: mt.t.c->say(); break;
case eD: mt.t.d->say(); break;
}
}
printf("--------------\n");
for(i=0; i<eMax; i++)
((Bs *)mt.tv[i])->say();
printf("--------------\n");
for(i=0; i<eMax; i++){
switch(i){
case eA: mt.t.a->call(); break;
case eB: mt.t.b->sing(); break;
}
}
printf("--------------\n");
}