title: how to calculate the one's complement for positive and negative number?
body: <p>If I use one's complement to represent number, what result should I get?<br>
  For example, number 01110 ( a positive number),its one's complement should be 01110 or 10001?<br>
  if the number is 10001 ( a negative number), the one's complement value is 01110?  </p>