int main(void)
      {
          int a = 48;
  
          printf("a = %d\n",a);      //顯示 a = 48
          printf("a = 0xx\n",a);  //顯示 a = 0x30
          return 0;
      }
      

      int main(void)
      {
         int a = 48, c, d;             c = a>>4;                       // c = 3
         d = a & 0xf;                    // d = 0
         printf("c = %d, d = %d\n",c ,d);
         return 0;
    
      }