enum可以做索引

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。

点击(此处)折叠或打开

1. MoTbl.cpp
2. #include <stdio.h>
3. #include <stdlib.h>
4. enum {
5. eA=0,
6. eB,
7. eC,
8. eD,
9. eMax
10. };
11. class Bs{
12. public:
13. virtual void say(){ printf("Bs\n"); }
14. };
15. class A: public Bs{
16. int aa[1];
17. public:
18. void say(){printf("A\n");}
19. void call(){printf("A::call\n");}
20. };
21. class B: public Bs{
22. int aa[3];
23. public:
24. void say(){printf("B\n");}
25. void sing(){printf("B::sing\n");}
26. };
27. class C: public Bs{
28. int aa[10];
29. public:
30. void say(){printf("C\n");}
31. };
32. class D: public Bs{
33. int aa[100];
34. public:
35. void say(){printf("D\n");}
36. };
37. class MoTbl{
38. public:
39. union{
40. struct{
41. A *a;
42. B *b;
43. C *c;
44. D *d;
45. }t;
46. void *tv[eMax];
47. };
48. };
49. int
50. main ( int argc, char *argv[] )
51. {
52. int i = 0;
53. MoTbl mt;
54. A a;
55. B b;
56. C c;
57. D d;
58. printf("A:%d\n",sizeof(MoTbl));
59. for(i=0; i<eMax; i++)
60. printf("%p\n",mt.tv[i]);
61. printf("--------------\n");
62. mt.tv[eA] = &a;
63. mt.tv[eB] = &b;
64. mt.tv[eC] = &c;
65. mt.tv[eD] = &d;
66. for(i=0; i<eMax; i++)
67. printf("%p\n",mt.tv[i]);
68. printf("--------------\n");
69. mt.t.a->say();
70. printf("--------------\n");
71. for(i=0; i<eMax; i++){
72. 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>
    4. enum {
    5. eA=0,
    6. eB,
    7. eC,
    8. eD,
    9. eMax
    10. };
    11. class Bs{
    12. public:
    13. virtual void say(){ printf("Bs\n"); }
    14. };
    15. class A: public Bs{
    16. int aa[1];
    17. public:
    18. void say(){printf("A\n");}
    19. void call(){printf("A::call\n");}
    20. };
    21. class B: public Bs{
    22. int aa[3];
    23. public:
    24. void say(){printf("B\n");}
    25. void sing(){printf("B::sing\n");}
    26. };
    27. class C: public Bs{
    28. int aa[10];
    29. public:
    30. void say(){printf("C\n");}
    31. };
    32. class D: public Bs{
    33. int aa[100];
    34. public:
    35. void say(){printf("D\n");}
    36. };
    37. class MoTbl{
    38. public:
    39. union{
    40. struct{
    41. A *a;
    42. B *b;
    43. C *c;
    44. D *d;
    45. }t;
    46. void *tv[eMax];
    47. };
    48. };
    49. int
    50. main ( int argc, char *argv[] )
    51. {
    52. int i = 0;
    53. MoTbl mt;
    54. A a;
    55. B b;
    56. C c;
    57. D d;
    58. printf("A:%d\n",sizeof(MoTbl));
    59. for(i=0; i<eMax; i++)
    60. printf("%p\n",mt.tv[i]);
    61. printf("--------------\n");
    62. mt.tv[eA] = &a;
    63. mt.tv[eB] = &b;
    64. mt.tv[eC] = &c;
    65. mt.tv[eD] = &d;
    66. for(i=0; i<eMax; i++)
    67. printf("%p\n",mt.tv[i]);
    68. printf("--------------\n");
    69. mt.t.a->say();
    70. printf("--------------\n");
    71. for(i=0; i<eMax; i++){
    72. switch(i){
    73. case eA: mt.t.a->say(); break;
    74. case eB: mt.t.b->say(); break;
    75. case eC: mt.t.c->say(); break;
    76. case eD: mt.t.d->say(); break;
    77. }
    78. }
    79. printf("--------------\n");
    80. for(i=0; i<eMax; i++)
    81. ((Bs *)mt.tv[i])->say();
    82. printf("--------------\n");
    83. for(i=0; i<eMax; i++){
    84. switch(i){
    85. case eA: mt.t.a->call(); break;
    86. case eB: mt.t.b->sing(); break;
    87. }
    88. }
    89. printf("--------------\n");
    90. }

    输出

    点击(此处)折叠或打开

    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. --------------
73. case eA: mt.t.a->say(); break;
74. case eB: mt.t.b->say(); break;
75. case eC: mt.t.c->say(); break;
76. case eD: mt.t.d->say(); break;
77. }
78. }
79. printf("--------------\n");
80. for(i=0; i<eMax; i++)
81. ((Bs *)mt.tv[i])->say();
82. printf("--------------\n");
83. for(i=0; i<eMax; i++){
84. switch(i){
85. case eA: mt.t.a->call(); break;
86. case eB: mt.t.b->sing(); break;
87. }
88. }
89. printf("--------------\n");
90. }

输出

点击(此处)折叠或打开

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. --------------