1 #include <stdio.h> 2 #include <stdlib.h> 3 4 #define NAME_STR_LEN 32 5 6 #define offsetof(type, member) (size_t)&(((type*)0)->member) 7 8 #define container_of(ptr, type, member) ({ 9 const typeof( ((type *)0)->member ) *__mptr = (ptr); 10 (type *)( (char *)__mptr - offsetof(type,member) );}) 11 12 typedef struct student_info 13 { 14 int id; 15 char name[NAME_STR_LEN]; 16 int age; 17 }student_info; 18 19 20 int main() 21 { 22 size_t off_set = 0; 23 off_set = offsetof(student_info, id); 24 printf("id offset: 蝈span>",off_set); 25 off_set = offsetof(student_info, name); 26 printf("name offset: 蝈span>",off_set); 27 off_set = offsetof(student_info, age); 28 printf("age offset: 蝈span>",off_set); 29 student_info *stu = (student_info *)malloc(sizeof(student_info)); 30 stu->age = 10; 31 student_info *ptr = container_of(&(stu->age), student_info, age); 32 printf("age:%d ", ptr->age); 33 printf("stu address:%p ", stu); 34 printf("ptr address:%p ", ptr); 35 return 0; 36 }
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