C# 0 The Complete Reference

PART I

C h a p t e r   4 :  

O p e r a t o r s  

81

PART IPART I

    Console.WriteLine("Value of n: " + n);

    // Multiply by 2.

    n = n << 1;

    Console.WriteLine("Value of n after n = n * 2: " + n);

    // Multiply by 4.

    n = n << 2;

    Console.WriteLine("Value of n after n = n * 4: " + n);

    // Divide by 2.

    n = n >> 1;

    Console.WriteLine("Value of n after n = n / 2: " + n);

    // Divide by 4.

    n = n >> 2;

    Console.WriteLine("Value of n after n = n / 4: " + n);

    Console.WriteLine();

    // Reset n.

    n = 10;

    Console.WriteLine("Value of n: " + n);

    // Multiply by 2, 30 times.

    n = n << 30; // data is lost

    Console.WriteLine("Value of n after left-shifting 30 places: " + n);

  }

}

The output is shown here:

Value of n: 10

Value of n after n = n * 2: 20

Value of n after n = n * 4: 80

Value of n after n = n / 2: 40

Value of n after n = n / 4: 10

Value of n: 10

Value of n after left-shifting 30 places: -2147483648

Notice the last line in the output. When the value 10 is left-shifted 30 times, information 

is lost because bits are shifted out of the range of an 

int

. In this case, the garbage value 

produced is negative because a 1 bit is shifted into the high-order bit, which is used as a 

sign bit, causing the number to be interpreted as negative. This illustrates why you must be 

careful when using the shift operators to multiply or divide a value by 2. (See Chapter 3 for 

an explanation of signed vs. unsigned data types.)