Java Recursive Decimal to Binary Function Printing Backwards

Question

I am coding a Lab exercise for one of my classes. The question asks to "Write a recursive function convert a decimal number into a binary number, printing the binary number" Using the constructor public static void decToBin(int num){}

Current code:

public class convert {
    public static void decToBin(int num) {
        if (num > 0) {
            decToBin(num /= 2);
            System.out.print(num % 2);
        }
    }

    public static void main(String[] args) {
        decToBin(50);
    }
}

Output: 011001

Unfortunately, when the program unpacks all the methods that were called and ends them it prints out my number in binary but backwards. I have tried just about everything under the sun and nothing works for me.

If anybody could tell me where the problem lies, give me a hint or anything. I just need a second opinion on this code. Thank you!

Not related, but wouldn't it print the wrong value for 1?

CBredlow
– CBredlow

2017-05-30 23:09:53 +00:00
Commented May 30, 2017 at 23:09 — CBredlow
– CBredlow, Commented May 30, 2017 at 23:09

Kevin · Accepted Answer · 2017-05-30 23:10:17Z

3

You're dividing by 2 before you print out your answer which is messing with the result. The corrected function would be.

public static void decToBin(int num) {
    if (num > 0) {
        decToBin(num / 2);
        System.out.print(num % 2);
    }
}

Then to reverse the order, you can flip the lines.

public static void decToBin(int num) {
    if (num > 0) {
        System.out.print(num % 2);
        decToBin(num / 2);
    }
}

answered May 30, 2017 at 23:10

Kevin

4106 silver badges16 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

BigChemist Over a year ago

Thank you Kevin, it turns out the ' /= ' was the problem and all it needed was to be changed to ' / '

Mohd · Accepted Answer · 2017-05-30 23:11:40Z

0

First of all, you need to print num % 2 before calling the function on num /= 2. and you need to reverse the output to get the binary number because when converting to binary you type the numbers from right to left.

answered May 30, 2017 at 23:11

Mohd

5,6317 gold badges22 silver badges31 bronze badges

Collectives™ on Stack Overflow

Java Recursive Decimal to Binary Function Printing Backwards

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related