offset

/*
 ============================================================================
 Name        : jk.c
 Author      : xuqianghong
 Version     :
 Copyright   : Your copyright notice
 Description : Hello World in C, Ansi-style
 ============================================================================
 */

#include <stdio.h>
#include <stdlib.h>

#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE* )0)->MEMBER)

typedef struct
{
int i;
int j;
char m;
char n;
}exp;

exp test = {1,2,'A','B'};

int main(void) {
puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */

void *p = &test.n;
void *xx = &(((exp *)0)->n);

void *yy = (exp *)((char *)p - (unsigned long)(xx));

return EXIT_SUCCESS;

}