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BitWise Operations in C#

Introduction

C# has lots of flexibility over manipulating with bits. Before I start explaining about bit wise manipulation I would like to give some inputs on binary operations.

Binary numbers

With only two symbols you can represent any type of information you want, these symbols can be {a,b}, {0,1} or the {beep, beeeep} of the Morse code. When you want to work with boolean (1) expressions or place multiple values in a single byte (group of 8 bit), it is more convenient for you to represent these bytes as binary numbers.

Binary numbers are specifically required to build bit-masks, used with boolean operators (AND, OR, XOR, NOT). In other words, 235 is the addition of 128+64+32+8+2+1. Binary numbers seem to be very long numbers, but they are much easier for a computer to handle since each bit, or binary digit can be represented by an electrical signal which is either on or off

128 64 32 16 8 4 2 1
      1 1 0 1 0

Using the above table you can see that the decimal number 11010 is equal to 26 in the decimal system. (16+8+2=26) - Use the base checker at the top to turn 26 into binary if you want to check.

Using binary notation is a very good exercise for Numerical Hour since the principles can be quickly taught - also some very interesting math's can be done quickly - e.g.

To half any number - simply move the digits 1 place to the right: 101100 = 44 , 10110=22
(what happens if there is a fractional part - Can you make a rule?)

To double a number - simply add a zero on the end: 1111 = 15, 11110 = 30 

Some of the important binary operations, which I am going to discuss, are following:

AND operation

OR operation

Shift operations

As we know in binary all 1's are true and 0's are considered to be false.

When AND operations is done on the binary value following are the results of AND.

Following is the truth table for AND operation.

A B AND
0 (false) 0 (false) 0 (false)
1(True) 0 (false) 0 (false)
0 (false) 1(True) 0 (false)
1(True) 1(True) 1(True)

*When using AND operation it gives True only when both the values are True.

In C# to implement the AND operation using '&' Operator.

Now let's see e first program

Program 1

using System;
class MyClass {
    public static void Main() {
        byte varA = 10; // binary equivalent for 10 is 01010
        byte varB = 20; // binary equivalent for 20 is 10100
        long result = varA & varB; // AND operation result should be 00000
        Console.WriteLine("{0} AND {1} Result :{2}", varA, varB, result);
        varA = 10; // binary equivalent for 10 is 01010
        varB = 10; // binary equivalent for 10 is 01010
        result = varA & varB; // AND operation result should be 01010
        //so the result will contain 10 in decimal
        Console.WriteLine("{0} AND {1} Result : {2}", varA, varB, result);
    }
}

Program Output:

C:\csharp\progs>bitprg1

10  AND  20 Result :0
10  AND  10 Result : 10 

When OR operations is done on the binary value following are the results of OR.

Following is the truth table for OR operation.

A B OR
0 (false) 0 (false) 0 (false)
1(True) 0 (false) 1(True)
0 (false) 1(True) 1(True)
1(True) 1(True) 1(True)

*When using OR operation it gives FALSE only when both the values are FALSE. In all other cases OR operation gives true.

In C# to implement the OR operation using '|' Operator.

Now let's see e first program

Program 2

using System;
class MyClass {
    public static void Main() {
        byte varA = 10; // binary equivalent for 10 is 01010
        byte varB = 20; // binary equivalent for 20 is 10100
        long result = varA | varB; // OR operation result should be 11110
        //so the result will contain 30 in decimal
        Console.WriteLine("{0} OR {1} Result :{2}", varA, varB, result);
        varA = 10; // binary equivalent for 10 is 01010
        varB = 10; // binary equivalent for 10 is 01010
        result = varA | varB; // OR operation result should be 01010
        //so the result will contain 10 in decimal
        Console.WriteLine("{0} OR {1} Result : {2}", varA, varB, result);
    }
}

Program 2 output:

C:\csharp\progs>bitprg2

10  OR  20 Result :30
10  OR  10 Result : 10 

There are two kinds of Shift operations on Right Shift and Left Shift.

Right Shift operation is used for shifting the bits positions towards right side.

Left Shift operation is used for shifting the bits positions towards left side.

When Right Shift operations are done on a binary value the bits are shifted to one position towards right side.

Let's take an example:

The binary equivalent for the decimal value 10 is 1010. So when Right Shift operation is done this value. All the bits will move one position towards right so the right most bits will be truncated and left most bits is filled with zero.

1010 when shifted to right one position its value will be 0101

So the decimal equivalent for 0101 is 5. This means when decimal value 10 shifted to right one position its value is reduced to 5.

In C# to implement the Right shift operation using '>>' Operator.

Now let's see e first program

Program 3

using System;
class MyClass {
    public static void Main() {
        byte varA = 10; // binary equivalent for 10 is 01010
        long result = varA >> 1; // Right Shift operation result should be 0101
        //so the result will contain 5 in decimal
        Console.WriteLine("{0} is Right Shifted to 1 position Result :{1}", varA, result);
    }
}

Program 3 output:

C:\csharp\progs>bitprg3

10 is Right Shifted to 1 position Result :5

When Left Shift operations are done on a binary value the bits are shifted to one position towards left side.

Let's take an example:

The binary equivalent for the decimal value 10 is 1010.

So when left Shift operation is done this value. The all the bits will move one position towards left so the left most bit will be truncated and right most bit is filled with zero.1010 when shifted to right one positions its value will be 10100.

So the decimal equivalent for 10100 is 20. This means when decimal value 10 shifted to left one position its value is increased to 20.

In C# to implement the Left shift operation using '<<' Operator.

Now let's see e first program

Program 4

using System;
class MyClass {
    public static void Main() {
        byte varA = 10; // binary equivalent for 10 is 01010
        long result = varA << 1; // Left Shift operation result should be 10100
        //so the result will contain 20 in decimal
        Console.WriteLine("{0} is Left Shifted to 1 position Result :{1}", varA, result);
    }
}

Program 4 output:

C:\csharp\progs>bitprg4

10 is Left Shifted to 1 position Result :20

Further reading

1. .Net  More information on .Net technologies 


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