val = b << 8 | a; //0x52=01010010左移8位为：010100100000000 =010100100000000|01001000 =0101001001001000 =0x5248 //16进制 =21064 //10进制

unsigned long val = 0; char a = 0x48; char b = 0x52; val = b << 8 | a; £¯£¯这里如何理解 ?