CODEWITHSUNDEEP
javabinary
Scuffed Newton
Scuffed Newton

Reputation: 87

I'm trying to convert a binary number to a decimal number but my Output is always 0

Here is my code. I tried to Convert the binary to a Char array, then multiply each char in the array by 2 to the power of its corresponding number in the array, then sum up all the values of the char array into a double. New to programming so a bit confused. My input Binary is txfBinaryInput, and my output label is lblDisplay.

 private void btnProcessActionPerformed(java.awt.event.ActionEvent evt)                                           
{                                               
    if (txfBinaryInput.getText().equals(""))
    {
        lblDisplay.setText("ERROR: NO INPUT");
    } else
    {
        int n = 0;
        int[] binaryValueStorage = new int[100];
        double[] decimalValueStorage = new double[100];
        String binaryInput = txfBinaryInput.getText();
        int binaryNumber = binaryInput.length();
        char[] binaryDigits = binaryInput.toCharArray();
        for (int i = 0; i >= binaryNumber; i++)

        {
            binaryValueStorage[n] = binaryDigits[n];
            decimalValueStorage[n] = binaryValueStorage[n] * (Math.pow(2, n));
            n++;
        }
        double sum = 0;
        for (double a : decimalValueStorage)
        {
            sum += a;
        }
        lblDisplay.setText("The Deciaml Value Is " + sum);
    }
}

Upvotes: 1

Views: 82

Answers (2)

CryptoFool
CryptoFool

Reputation: 23079

Well, this is a lot to throw at you, but this is how I'd attack this problem:

public class BinaryToDecimalTest {

    private static long binaryToDecimal(String binaryInput)
    {
        long sum = 0;
        for (int i = 0 ; i < binaryInput.length() ; i++) {
            sum *= 2;
            if (binaryInput.charAt(i) == '1')
                sum += 1;
        }
        return sum;
    }

    private static void test(String binaryInput) {
        long n = binaryToDecimal(binaryInput);
        System.out.println(String.format("The Deciaml Value of %s Is %d", binaryInput, n));
    }

    public static void main(String...args) {
        test("0100");
        test("1011");
        test("1011");
        test("10000000");
        test("10000000000000000");
    }
}

Result:

The Deciaml Value of 0100 Is 4
The Deciaml Value of 1011 Is 11
The Deciaml Value of 1010 Is 10
The Deciaml Value of 10000000 Is 128
The Deciaml Value of 10000000000000000 Is 65536

I don't want to just hit you with code, but I didn't know where to start given all of the issues with your code. I wanted you to see how directly you can often attack a problem. I'd be happy to keep working with you, and explain what's going on here.

The one dirty trick I'm using is multiplying the entire accumulated sum by two each time around. This lets you work naturally from the front of the array, rather than having to work your way backwards. The first digit gets multiplied by 2 (length - 1) times, the second (length - 2) times, etc., down to the last number, which doesn't get multiplied at all.

Upvotes: 0

Anis R.
Anis R.

Reputation: 6902

Beware: in your for loop condition, you have i >= binaryNumber instead of i < binaryNumber, therefore your program will never enter the loop!

And on a side note, why are you using two variables, i and n, for the same purpose (incrementing and accessing the array)?

Edit: another issue:

In binary numbers, lower order bits are to the right, but in arrays, indices are from left to right!!

So you want your rightmost digit to be multiplied by 2^0, the next one right to its left by 2^1, and so on.

But in your code, what is happening is the opposite: it is the leftmost digit (your digit at index 0) that is being multiplied by 2^0!

To fix, you can either:

1) reverse your binaryDigits array before starting to convert, and keep the rest of your code untouched

2) replace decimalValueStorage[n] = binaryValueStorage[n] * (Math.pow(2, n)); by decimalValueStorage[n] = binaryValueStorage[n] * (Math.pow(2, binaryNumber - n));

Hope this helps!

Upvotes: 2

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