在工作中，經常遇到按位（bit）定義結構體 的情況。由於一個位元組有8個位，這時，程式設計師往往對bit的位置產生困惑。現在給出一個例子，來說明位的定義次序。

#pragma pack(push,1)

typedef struct ST_TEST
{
	unsigned char	ucA:1;
	unsigned char	ucB:1;
	unsigned char	ucC:1;
	unsigned char	ucD:1;
	unsigned char	ucE:1;
	unsigned char	ucF:1;
	unsigned char	ucG:1;
	unsigned char	ucH:1;
} ST_TEST;
#pragma pack(pop)

#include <string.h>
#include <stdio.h>
int main(void)
{
	ST_TEST stTest;
	stTest.ucA = 1;
	stTest.ucB = 0;
	stTest.ucC = 0;
	stTest.ucD = 0;
	stTest.ucE = 0;
	stTest.ucF = 0;
	stTest.ucG = 1;
	stTest.ucH = 0;

	unsigned char ucTest;
	memcpy(&ucTest, &stTest, 1);
	//沒有現成的列印二進位制的方法，所以用16進位制列印
	printf("%x", ucTest);

	scanf("%c", &ucTest);
	return 0;
}