字节翻转

unsigned char invert(unsigned char a)
{
 unsigned char c = 0;
 
 unsigned char bitmask = 1;
 int i;
 for(i = 0; i < 8; i++)
 {
  c = (c << 1) | (a & bitmask);
  a = a >> 1; 
 }
 return c;
}

int main()
{
 printf("%x", invert(0x12));
 return 0;
}