// 位段赋值的例子

#include <stdio.h>

int main()
{
	unsigned char puc[4];
	struct tagPIM
	{
		unsigned char ucPiml;
		unsigned char ucData0 : 1;
		unsigned char ucData1 : 2;
		unsigned char ucData2 : 3;
	}*pstPimData;
	pstPimData = (struct tagPIM*)puc;
	memset(puc, 0, 4);//全部置0
	pstPimData->ucPiml = 2;//0000 0010全部取出
	pstPimData->ucData0 = 3;//0000 0011取出1
	pstPimData->ucData1 = 4;//0000 0100取出00
	pstPimData->ucData2 = 5;//0000 0101取出101
	// 0000 0000 0000 0000 0000 0000 0000 0000
	// 0000 0010 0010 1001 0000 0000 0000 0000
	// 0    2    2    9    0    0    0    0   
	// 结果即 02 09 00 00
	printf("%02x %02x %02x %02x\n", puc[0], puc[1], puc[2], puc[3]);
	return 0;
}

<img src="https://img-blog.csdn.net/20150511153114682?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhb3lhcWlhbjU1Mg==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />