通过结构体成员获得结构体地址

通过结构体的成员获得结构体的地址，摘自kernel的一段宏，为了理解container_of,写了个例子

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#define container_of(ptr, type, member) ({ \
     const typeof( ((type *)0)->member ) *__mptr = (ptr); \
     (type *)( (char *)__mptr - offsetof(type,member) );})

struct example{
unsigned char ea;
int eb;
int ec;
};

int main()
{
        struct example *example=malloc(sizeof(struct example));
        memset(example,0,sizeof(struct example));
        printf("%p\n",example);
        printf("%p\n",&(example->ec));
        printf("%p\n",(void *)offsetof(struct example,ec));
        printf("%p\n",container_of(&(example->ec),struct example,ec));
        free(example);
        example=NULL;
        return 0;
}