Modulus vs Bit manipulation &

When converting a decimal number to hexadecimal, I always use modulus. There is another way of doing this.

• Mod operation

int digit = num % 16

• Bit operation

int digit = num & 15

查表法

將所有元素臨時存起來，建立對應關系，每一次將&15后的值作為索引去查表，就可找到對應的元素。

char[] chs = {'0','1','2','3',
              '4','5','6','7',
              '8','9','A','B',
              'C','D','E','F'};