Binary to Decimal number converter in JAVA?

Question

What is the problem with my code. It prints 1 for any value of input.

package Assign;
import java.util.Scanner;
import java.lang.*;

public class Assignment {

public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
    int num = s.nextInt();
    int x = 1;
    int sum = 1, i = 0;

    while (num > 0) {
        x = num % 10;
        if (x == 1) {
            sum = sum + (2 * i);
        }
        num = num / 10;
        i++;
    }
    System.out.println(sum);
}
}

When you debugged this code, what exactly did you see that didn't make sense? — takendarkk, Aug 28 '17 at 20:28
Look at `x`. You save the value of an operation in it, but then never save the value of that operation. Start there. — Frecklefoot, Aug 28 '17 at 20:32

score 0 · Answer 1 · answered Aug 28 '17 at 20:39

0

Two problems:

1) You need to add 2^i to sum, not 2*i

2) Sum starts at 1 instead of 0, meaning the answer will always be 1 more than it should be.

answered Aug 28 '17 at 20:39

EKW

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JensS · Answer 2 · 2017-08-28T21:23:04.263

0

If you do not need to develop the algorithm yourself, here is a shorter way to do it:

System.out.println(new BigInteger(String.valueOf(num), 2));

edited Aug 28 '17 at 21:23

answered Aug 28 '17 at 20:46

JensS

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2
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You should include more context/explanation for your code - please see [answer]. – EJoshuaS - Stand with Ukraine Aug 28 '17 at 21:09

score 0 · Answer 3 · answered Aug 28 '17 at 20:54

0

A simple way to do this.

System.out.println(Integer.parseInt(binaryString,2));

answered Aug 28 '17 at 20:54

Rohit-Pandey

2,039
17
24

You should include more context/explanation - please see [answer]. – EJoshuaS - Stand with Ukraine Aug 28 '17 at 21:09
A good java programmer can understand it easily. – Rohit-Pandey Aug 29 '17 at 05:06

Karthik Reddy V V · Answer 4 · 2017-08-29T06:44:05.233

In the program the only case where the variable sum is getting modified when (num > 0) is in the if block. Considering the if block

if (x == 1) {
   sum = sum + (2 * i);
}

since the variable i = 0.

sum = sum + (2 * i);

evaluates to

sum = sum + (2 * 0);
sum = sum + 0;
sum = sum;

since the variable sum = 1, the output is always 1.

Considering the other possibility, when (num <= 0) where while loop is skipped, since sum = 1, the output is 1.

For Binary to Decimal number converter in Java check out

http://www.java2novice.com/java-interview-programs/binary-to-decimal/

Binary to Decimal number converter in JAVA?

4 Answers4