Write a c program to count the number of 1bits in an unsigned integer.

// program in C.

// header

#include <stdio.h>  

// main function

int main()

{

   // variables

unsigned int n;

unsigned int count = 0;

// ask to enter an unsigned integer

printf("Enter an unsigned integer:");

// read integer

scanf("%d",&n);

int nn=n;

// find the set bits

while (n)

   {

count += n & 1;

n >>= 1;

   }

   // print set bits

printf("number of 1bits in number %d are: %d ",nn,count);

return 0;

}

Explanation:

Read an unsigned integer from user and assign it to variable "n".Initialize a variable "count=0" to store the count of set bits.Loop through all the bits of number,If bits is set the increment the count by 1.To check  a bit is set, find "bitwise and" of number with 1.then right shift the number  by 1. Repeat this for all the bits of number (until n equals to 0).

Output:

Enter an unsigned integer:15                                                                                              

number of 1bits in number 15 are: 4