C# 0 The Complete Reference

PART I

C h a p t e r   4 :  

O p e r a t o r s  

75

PART IPART I

num: 10

num after turning off bit zero: 10

The value 

0xFFFE

 used in the AND statement is the hexadecimal representation of 

1111 1111 1111 1110. Therefore, the AND operation leaves all bits in 

num

 unchanged except 

for bit zero, which is set to zero. Thus, even numbers are unchanged, but odd numbers are 

made even by reducing their value by 1.

The AND operator is also useful when you want to determine whether a bit is on or off. 

For example, this program determines if a number is odd:

//  Use bitwise AND to determine if a number is odd.

using System;

class IsOdd {

  static void Main() {

    ushort num;

    num = 10;

    if((num & 1) == 1)

      Console.WriteLine("This won't display.");

    num = 11;

    if((num & 1) == 1)

      Console.WriteLine(num + " is odd.");

  }

}

The output is shown here:

11 is odd.

In the