flag在c语言中标识某种状态或记录某种信息，可以通过修改flag中来控制程序流程,判断某种状态是否存在或记录某种信息
操作:(1)初始化 (2)赋值 (3)判断 (4)修改 (5)去初始化

#include <stdlib.h>

int power_state_check;
 
int main()
{
    int i = 0;
     
    power_state_check = 0x10;
    
    if(power_state_check&0x10)
    {
        power_state_check |= (1<<0);
    }
    
    if(power_state_check&0x10)
    {
        power_state_check |= (1<<1);
    }
    
    if(power_state_check&0x10)
    {
        power_state_check |= (1<<2);
    }
    
    if(power_state_check&0x10)
    {
        power_state_check |= (1<<3);
    }
    
    if(power_state_check&0x10)
	{
	    printf("Hello, World power_state_check is %x\n",power_state_check);
		for(i=0;i<4;i++)
		{
			if((power_state_check&(1<<i)) == 0x0)
			{
			   printf("i =%d cmd loss func %s line %d\r\n",i,__func__,__LINE__);
				if(i==2)
				{
					printf(" i=%d cmd loss func  msg_match enter operation %s line %d\r\n",i,__func__,__LINE__);
				}
			}
		}

	}
	power_state_check = 0x0;
    
    printf("Hello, World power_state_check is %d\n",power_state_check);
    return(0);
}