C Program to Check if a given Integer is Power of 2 using Bitwise Operators

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This is a C Program to check if a given integer is power of 2 using bitwise operators.

Problem Description

This C Program checks if a given integer is power of 2 using bitwise operators.

Problem Solution

Take input from the user and performs bitwise operations as shown in the program below.

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Program/Source Code

Here is source code of the C Program to check if a given integer is power of 2 using bitwise operators. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

/*
 * C Program to Check if a given Integer is Power of 2 using Bitwise Operators
 */
#include <stdio.h>
#define NUM_BITS_INT (8*sizeof(int))
 
int power_of_2(unsigned int);
 
int main()
{
    unsigned int num;
 
    printf("\nEnter Number");
    scanf("%d", &num);
    power_of_2(num);
}
 
/*
 * Finding the power of 2 using bit wise operators
 */ 
int power_of_2(unsigned int x)
{
    int i, count = 0, result, shift_num;
 
    for (i = 0;i <= NUM_BITS_INT;i++)
    {
        shift_num = x >> i;
        result = shift_num & 1;
        if (result == 1)
            count++;
    }
    /*
     *If number of bits set to 1 are odd then the number is power of 2
     *If number of bits set to 0 are even then the number is not power of 2
     */
    if (count % 2 == 1)
        printf("YES");
    else 
        printf("NO");
}
Program Explanation

In this C Program, we are reading the number using ‘num’ variable. The power_of_2() function is used for finding the power of 2 using bit wise operators. Binary Right Shift operator the left operands value is moved right by the number of bits specified by the right operands and assign the value to ‘shift_num’ variable.

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The ‘result’ variable is used compute the Binary AND operation by copying a bit to the result if it exists in both operands. If condition statement is used to check the value of ‘res’ variable is equal to 1. If the condition is true then execute the statement and increment the value of ‘count’ variable.

If else condition statement is used to check that the number of bits set to 1 is odd and print the number is power of 2. Otherwise, if the condition is false and print the number is not power of 2 and displays the output of the program.

Runtime Test Cases
 
$ gcc bit25.c
$  a.out
Enter Number128
YES
$  a.out
Enter Number126
NO

Sanfoundry Global Education & Learning Series – 1000 C Programs.

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Here’s the list of Best Reference Books in C Programming, Data-Structures and Algorithms

If you wish to look at programming examples on all topics, go to C Programming Examples.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn