CODEWITHSUNDEEP
java
AAnwar007
AAnwar007

Reputation: 43

Binary counter for loop

/**
 * Created by abdul on 10/31/2016.
 */
import java.util.Arrays;
import java.util.Scanner;
public class BitCount {
    public static void main(String[] args) {
         Scanner in = new Scanner(System.in);
         System.out.println("Enter Cases:");
         int cases = in.nextInt();

    for (int i = 0; i < cases; i++) {
        int a = in.nextInt();
        String binary = Integer.toBinaryString(a);
        String[] nums = {binary};
        int count = 0;
        for (int j = 0; j < nums.length; j++) {
            //System.out.println(Arrays.toString(nums));
            if (nums[j].equals("1"))
                count++;
        }
        System.out.println(count);
    }
}

This is a problem from Code Abbey Called Bit Count As you probably know, all values inside a computer are represented in binary system. In this simple task you are to write a program which counts the number of non-zero bits in a given value.

We are using 32-bit integer values, so there should be from 0 to 32 non-zero bits. http://www.codeabbey.com/index/task_view/bit-count Could you please help me understand why my loop is only incrementing once and not incrementing through the entire thing?

Upvotes: 1

Views: 3477

Answers (1)

nhouser9
nhouser9

Reputation: 6780

You do this:

    int a = in.nextInt();
    String binary = Integer.toBinaryString(a);
    String[] nums = {binary};

Let's imagine you enter "4". What happens?

  1. First the number 4 gets stored in a.
  2. Then the string "000100" or something similar gets stored in the string binary.
  3. Then you create an array with one element, that element is equal to the string binary.

What you are trying to do is create an array of each digit of the string, but you actually create a single element array that simply stores another copy of the string you already computed! Try this instead:

    int a = in.nextInt();
    String binary = Integer.toBinaryString(a);
    int count = 0;
    for (int j = 0; j < binary.length(); j++) {
        //System.out.println(Arrays.toString(nums));
        if (binary.charAt(j) == '1')
            count++;
    }
    System.out.println(count);

This will check each character of the binary string for the digit 1.

Upvotes: 2

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