获取设置一个字节某一个位的数值

void print2(unsigned char a)
{
    int r[8];
    r[0] = ( a & (0x01 << 0)) >> 0; // 最低位
    r[1] = ( a & (0x01 << 1)) >> 1;
    r[2] = ( a & (0x01 << 2)) >> 2;
    r[3] = ( a & (0x01 << 3)) >> 3;
    
    r[4] = ( a & (0x01 << 4)) >> 4;
    r[5] = ( a & (0x01 << 5)) >> 5;
    r[6] = ( a & (0x01 << 6)) >> 6;
    r[7] = ( a & (0x01 << 7)) >> 7;  // 最高位
    
    printf("%d %d %d %d   %d %d %d %d\n",r[7],r[6],r[5],r[4],r[3],r[2],r[1],r[0]);
}



int main(void)
{
    unsigned char a = 0xBF;
    print2(a);
    
    unsigned char b = a | (0x01 << 6); //set on
    print2(b);
    
   b = a | (0x01 << 2); //set off 1
   unsigned char c = b ^ (0x01 << 2); //set off 2 ( 先set on 在 ^ )
    print2(c);
}

output:

1 0 1 1   1 0 1 1   //0xBF
1 1 1 1   1 1 1 1
1 1 1 1   1 0 1 1