C语言中的共用体
共用体又叫联合体
#include <stdio.h>
#include <stdlib.h>
union Test
{
unsigned char a;
unsigned short b;
unsigned int c;
};
union Test1
{
unsigned char a;
unsigned short b;
unsigned int c;
double d;
};
int main()
{
//共用体的大小为最大成员的大小
printf("union Test = %u\n", sizeof(union Test));
printf("union Test1 = %u\n", sizeof(union Test1));
//共用体公有一块内存，所有成员的地址都一样
union Test obj;
printf("%p, %p, %p, %p\n", &obj, &obj.a, &obj.b, &obj.c);
//给某个成员赋值，会影响到另外的成员
//左边是高位，右边是低位
//小端模式是高位放高地址，低位放低地址
obj.c = 0x44332211;
printf("%x\n",obj.c);
printf("%x\n",obj.b);
printf("%x\n",obj.a);
return 0;
}
结果：
union Test = 4
union Test1 = 8
0060FF0C, 0060FF0C, 0060FF0C, 0060FF0C
44332211
2211
11