快速获取结构体成员大小

1. #include <stdio.h>   
   
2. 
   
3. // 获取结构体成员大小
   
4. #define  GET_MEMBER_SIZE(type, member)   sizeof(((type*)0)->member)
   
5. 
   
6. // 获取结构体成员偏移量
   
7. #define  GET_MEMBER_OFFSET(type, member)  ((size_t)(&(((type*)0)->member)))
   
8. 
   
9. typedef struct _test_struct0
   
10. {
    
11. char x;  
    
12. char y;
    
13. char z;
    
14. }test_struct0;
    
15. 
    
16. typedef struct _test_struct1
    
17. {
    
18. char a;  
    
19. char c;
    
20. short b;         
    
21. int d;
    
22. test_struct0 e;
    
23. }test_struct1;
    
24. 
    
25. int main(int arc, char *argv[])
    
26. {
    
27. printf("GET_MEMBER_SIZE(test_struct1, a) = %ld\n", GET_MEMBER_SIZE(test_struct1, a));
    
28.     printf("GET_MEMBER_SIZE(test_struct1, c) = %ld\n", GET_MEMBER_SIZE(test_struct1, c));
    
29. printf("GET_MEMBER_SIZE(test_struct1, b) = %ld\n", GET_MEMBER_SIZE(test_struct1, b));
    
30. printf("GET_MEMBER_SIZE(test_struct1, d) = %ld\n", GET_MEMBER_SIZE(test_struct1, d));
    
31.     printf("GET_MEMBER_SIZE(test_struct1, e) = %ld\n", GET_MEMBER_SIZE(test_struct1, e));
    
32.     printf("test_struct1 size = %ld\n", sizeof(test_struct1));
    
33. 
    
34. printf("GET_MEMBER_OFFSET(a): %ld\n", GET_MEMBER_OFFSET(test_struct1, a));
    
35. printf("GET_MEMBER_OFFSET(c): %ld\n", GET_MEMBER_OFFSET(test_struct1, c));
    
36. printf("GET_MEMBER_OFFSET(b): %ld\n", GET_MEMBER_OFFSET(test_struct1, b));
    
37. printf("GET_MEMBER_OFFSET(d): %ld\n", GET_MEMBER_OFFSET(test_struct1, d));
    
38. printf("GET_MEMBER_OFFSET(e): %ld\n", GET_MEMBER_OFFSET(test_struct1, e));
    
39. 
    
40. return 0;
    
41. }

复制代码

真不错，这种就可以用已有的库实现获取数组的大小，非常节省时间呢