参考:https://www.cnblogs.com/sggggr/p/15028904.html
define STRUCT_OFFSET(struct_object,e) (unsigned long)&(((struct_object*)0)->e)
如上宏的意义,获取结构体S中元素M,相对于首元素的偏移量。
#include <stdio.h>
#define STRUCT_OFFSET(s,m) ( (int)(&((s*)0)->m)) /* 定义获取结构成员相对偏移地址的宏 */
struct man
{
char name[63];
int year;
char son_name[59];
char son_year;
};
int main()
{
printf("name offset:%d\n",STRUCT_OFFSET( struct man, name ));
printf("year offset:%d\n",STRUCT_OFFSET( struct man, year ));
printf("son_name offset:%d\n",STRUCT_OFFSET( struct man, son_name ));
printf("son_year offset:%d\n",STRUCT_OFFSET( struct man, son_year ));
return 0;
}
程序结果:
name offset:0
year offset:64
son_name offset:68
son_year offset:127