C++ Bitwise Operators

Most high-level language does not allow a bitwise operation because it is a machine level task. The bit is manipulated in memory to get the desired results using bitwise operators.

The list of bitwise operators are as follows

Bitwise OperatorsDescription
&Bitwise AND
|Bitwise OR
^Bitwise XOR
<<Bitwise left shift
>>Bitwise right shift
~Complement

Bitwise AND

A bitwise operation happens between two bits. A number is converted into a bit string and then bitwise operations performed on them.

The bitwise \hspace{3px} AND works similarly as logical \hspace{3px} AND. All output combination is show for bitwise \hspace{3px} AND below.

Let A and B be two variables with some one bit value, then:

ABOutput
111
100
010
000

The only time output is 1 when both A and B are 1.

For example, bitwise \hspace{3px} AND with 12 and 7 will result in following:

\begin{aligned}&1 \hspace{5px}1 \hspace{5px}0 \hspace{5px}0 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}12\\ \\
&0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}1 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}7\\ \\
&--------------\\ 
&0 \hspace{5px}1 \hspace{5px}0 \hspace{5px}0 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}4\\ 
&--------------\end{aligned}


The result is number 4.

Example Program: Bitwise AND

We now illustrate the correctness of the bitwise \hspace{3px}AND through a program.

#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{
    
    //Variable Declaration
    
    unsigned int a, b;
    unsigned int result;
    //Variable initialization
    
    a = 12;
    b = 7;
       
    result = a & b;
    //printing the results
       
    cout << " Output = " << " " << result << endl;
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Output = 4

Bitwise OR

The bitwise \hspace{3px} OR is similar to logical \hspace{3px} OR you learned earlier, except that it works at bit level. When a bitwise \hspace{3px}OR is performed on two bits – A and B, then the result is 1 if the bit value of A or B is 1. The bitwise operations are possible for more than two bits.

All combination of bit values is given below for bitwise \hspace{3px} OR.

ABOutput
111
101
011
000

For example,

If you want to perform bitwise \hspace{3px} OR operation on A = 14 and B = 3 then

\begin{aligned}&1 \hspace{5px}1 \hspace{5px}1 \hspace{5px}0 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}14\\ \\
&0 \hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}3\\ \\
&--------------\\ 
&1 \hspace{5px}1 \hspace{5px}1 \hspace{5px}1 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}15\\ 
&--------------\end{aligned}


Therefore, the output is 15.

Example Program: Bitwise OR

To verify the output from above example, we will write a program that computes using bitwise \hspace{3px} OR.

#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{
    //Variable declarations
    
    int a,b,result;
    
    //Variable initialization
    
    a = 14;
    b = 3;
    result = 0;
    
    // Bitwise OR operation
    
    result = a | b;
    
    //printing the results
    
    cout << "Output =" << " " << result << endl;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Output = 15

The output is what we expected.

Bitwise XOR (Exclusive-OR)

The bitwise \hspace{3px} XOR is a special kind of logical operation where two single bit inputs – A and B gives an output of 1 if either of them if is 1. Otherwise, the result is 0.

All combination of two inputs and a single output is given for bitwise \hspace{3px} XOR below.

ABOutput
110
101
011
000

Note how the output is 1 when either input is 1.

Let us see a manual example for bitwise \hspace{3px} XOR and later create a program that performs bitwise \hspace{3px} XOR to verify our output.

If A = 24 and B = 45 then bitwise \hspace{3px} XOR will result in following result.

\begin{aligned}&0 \hspace{5px}0 \hspace{5px}0\hspace{5px}1 \hspace{5px}1 \hspace{5px}0 \hspace{5px}0\hspace{5px}0 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}24\\ \\
&0 \hspace{5px}0 \hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}0 \hspace{5px}1\hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}45\\ \\
&-------------------\\ 
&0 \hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}53\\ 
&-------------------\end{aligned}


Therefore, the output 0011 \hspace{2px} 0101 is binary equivalent of 53.

Example Program: Bitwise XOR

#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{
    //Variable declarations
    
    int a,b,result;
    
    //Variable initialization
    
    a = 24;
    b = 45;
    result = 0;
    
    // Bitwise OR operation
    
    result = a ^ b;
    
    //printing the results
    
    cout << "Output =" << " " << result << endl;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Output = 53

Left Shift Operator (<<)

The value of the variable can be modified by changing the bits. This is achieved using bitwise shift operators.

The left \hspace{3px}shift\hspace{3px} operator modifies the value of variable by shifting the leftmost bits.

For example,

If A = 23 and you want to change the value of A using left \hspace{3px}shift\hspace{3px} operator ,

\begin{aligned}&0 \hspace{5px}0 \hspace{5px}0\hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}1 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}23 \\ \\
&0 \hspace{5px}0 \hspace{5px}1\hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}1 \hspace{5px}0 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}46 \hspace{5px}after\hspace{5px}1 \hspace{5px}bit \hspace{5px}left\hspace{5px} shift
\end{aligned}

Therefore, after shifting a single bit to the left, we get 46.

Example Program: Left Shift

#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{ 
    //Variable Declaration
     int A;
     
     // Variable initialization
     
     A = 23;
     
     //Bitwise Left Shift 
     
     A = A << 1;
     
     // Printing the results
     
     cout << "Output = " << " " << A << endl;
     
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Output = 46

It is not necessary that you have to shift only one bit, you can shift more than one to archive the desired results.

Right Shift Operator(>>)

The right\hspace{3px} shift \hspace{3px}operator is similar to left shift operator and it modify the value of a variable by shifting the rightmost bits.

For example,

If A = 23 and you want to shift rightmost bit then,

\begin{aligned}&0 \hspace{5px}0 \hspace{5px}0\hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}1 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}23 \\ \\
&0 \hspace{5px}0 \hspace{5px}0\hspace{5px}0 \hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}\backslash \backslash  Binary \hspace{5px}value\hspace{5px} of \hspace{5px}11\hspace{5px}after\hspace{5px}1 \hspace{5px}bit \hspace{5px}right\hspace{5px} shift
\end{aligned}

After shift 1 bit to the right we get 11.

Example Program: Right Shift Operator(>>)

#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{ 
    //Variable Declaration
     int A;
     
     // Variable initialization
     
     A = 23;
     
     //Bitwise Left Shift 
     
     A = A >> 1;
     
     // Printing the results
     
     cout << "Output = " << " " << A << endl;
     
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Output = 11

Complement(~)

The complement inverts the bits of a variable. If A = 44 with binary value 0010 \hspace{3px}1100 then the 1’s complement binary value is 1101 \hspace{3px}0011 which is 128 + 64 + 16 + 3 = 211.

The compiler gives the output in 2’s complement. To convert 1101 \hspace{3px}0011  into 2’s complement.

\begin{aligned}&1 \hspace{5px}1 \hspace{5px}0\hspace{5px}1 \hspace{5px}0 \hspace{5px}0 \hspace{5px}1 \hspace{5px}1 \hspace{5px}\\ \\
&0 \hspace{5px}0 \hspace{5px}0\hspace{5px}0 \hspace{5px}0 \hspace{5px}0 \hspace{5px}0 \hspace{5px}1 \hspace{5px}\\
&-----------------------\\ 
&1 \hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}0 \hspace{5px}1 \hspace{5px}0 \hspace{5px}0\hspace{5px}\backslash \backslash  Signed \hspace{5px} binary \hspace{5px}value\hspace{5px} of \hspace{5px}-45\\ 
&-----------------------
\end{aligned}

Example Program: Complement

#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{ 
    //Variable Declaration
     short int A;
          
     // Variable initialization
     
     A = 45;
     
     //Bitwise Left Shift 
     
     A = ~A;
     
     // Printing the results
     
     cout << "Output = " << " " << A << endl;
     
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Output = -45
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