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Count set bits in an integer in C++
We are given an integer number let’s say, num and the task is to firstly calculate the binary digit of a number and then calculate the total set bits of a number.
Set bits in a binary number is represented by 1. Whenever we calculate the binary number of an integer value then it is formed as the combination of 0’s and 1’s. So, the digit 1 is known as set bit in the terms of the computer.
Input − int number = 50
Output − Count of total set bits in a number are − 3
Explanation − Binary representation of a number 50 is 110010 and if we calculate it in 8-digit number then two 0’s will be appended in the beginning. So, the total set bits in a number are 3.
Input − int number = 10
Output − Count of total set bits in a number are − 2
Explanation − Binary representation of a number 10 is 00001010 and if we calculate it in 8-digit number then four 0’s will be appended in the beginning. So, the total set bits in a number are 2.
Approach used in the below program is as follows
Input the number in a variable of integer type
Declare a variable count to store the total count of set bits of type unsigned int
Start loop FOR from i to 1<<7 and i > 0 and i to i / 2
Inside the loop, check num & 1 == TRUE then print 1 else print 0
Start loop while to calculate the total count of bits till number isn’t 0
Inside the loop, set count = count + number & 1 and also set number >>=1
Print the count
Example
#include<iostream>
using namespace std;
//Count total set bits in a number
unsigned int bits(unsigned int number){
unsigned int count = 0;
unsigned i;
//display the total 8-bit number
cout<<"8-bit digits of "<<number<<" is: ";
for (i = 1 << 7; i > 0; i = i / 2){
(number & i)? cout<<"1": cout<<"0";
}
//calculate the total set bits in a number
while (number){
count += number & 1;
number >>= 1;
}
cout<<"\nCount of total set bits in a number are: "<<count;
}
int main(){
int number = 50;
bits(number);
return 0;
}Output
If we run the above code it will generate the following output −
8-bit digits of 50 is: 00110010 Count of total set bits in a number are: 3
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