#include <stdio.h>
#include <stdint.h>

union u{
uint32_t u32[8];
uint8_t u8[32];
};

int main(void)
{
union u u1 = { .u8 = {0} };
uint8_t *u8 = &u1.u8[8];
printf("%08x\n",u1.u32[2]);
*u8 = 0xff;
printf("%08x\n",u1.u32[2]);
}