C语言，struct 结构体、union共用体的使用

//状态字节，根据数据定义几个标志，标志位依据联合体内部结构体进行变量定义

//目的，节省内存空间，省去特定字节

struct STATDATA
{
	union
	{
		unsigned char stat;
		struct 
		{
			unsigned stat0:1;
			unsigned stat1:1;
			unsigned stat2:1;
			unsigned stat3:1;
			unsigned stat4:1;
			unsigned stat5:1;
			unsigned stat6:1;
			unsigned stat7:1;
		};
	};
};
struct STATDATA STATDATA1;
struct STATDATA STATDATA2;


int main(void)
{
	STATDATA1.stat = 0x55;
	STATDATA2.stat = 0xAA;
	printf("STATDATA1.stat0 = %d\n",STATDATA1.stat0);
	printf("STATDATA1.stat1 = %d\n",STATDATA1.stat1);
	printf("STATDATA1.stat2 = %d\n",STATDATA1.stat2);
	printf("STATDATA1.stat3 = %d\n",STATDATA1.stat3);
	printf("STATDATA1.stat4 = %d\n",STATDATA1.stat4);
	printf("STATDATA1.stat5 = %d\n",STATDATA1.stat5);
	printf("STATDATA1.stat6 = %d\n",STATDATA1.stat6);
	printf("STATDATA1.stat7 = %d\n",STATDATA1.stat7);
	printf("STATDATA2.stat0 = %d\n",STATDATA2.stat0);
	printf("STATDATA2.stat1 = %d\n",STATDATA2.stat1);
	printf("STATDATA2.stat2 = %d\n",STATDATA2.stat2);
	printf("STATDATA2.stat3 = %d\n",STATDATA2.stat3);
	printf("STATDATA2.stat4 = %d\n",STATDATA2.stat4);
	printf("STATDATA2.stat5 = %d\n",STATDATA2.stat5);
	printf("STATDATA2.stat6 = %d\n",STATDATA2.stat6);
	printf("STATDATA2.stat7 = %d\n",STATDATA2.stat7);
	
	return 0;
}

// 输出结果：

// STATDATA1.stat0 = 1

// STATDATA1.stat1 = 0

// STATDATA1.stat2 = 1

// STATDATA1.stat3 = 0

// STATDATA1.stat4 = 1

// STATDATA1.stat5 = 0

// STATDATA1.stat6 = 1

// STATDATA1.stat7 = 0

// STATDATA2.stat0 = 0

// STATDATA2.stat1 = 1

// STATDATA2.stat2 = 0

// STATDATA2.stat3 = 1

// STATDATA2.stat4 = 0

// STATDATA2.stat5 = 1

// STATDATA2.stat6 = 0

// STATDATA2.stat7 = 1