__attribute__ ((packed)) 对齐或者取消对齐实例，注意摆放位置，不然没办法跟编译器好好讲话

#include<stdio.h>#include<stdlib.h>typedef struct{char a;short b;int c;}__attribute__ ((packed)) sttest  ;/*__attribute__ ((packed));*/int main(void){char stsize;sttest stTest;void *addra,*addrb,*addrc;               stsize =  sizeof(sttest);addra = &stTest.a;addrb = &stTest.b;addrc = &stTest.c;printf("stsize is %d\n",stsize);printf("a is %d\n",addra);printf("a is %d\n",addrb);printf("a is %d\n",addrc);return 0;}