# Binary to Decimal conversion

• 12-31-2011, 04:51 PM
mrashi12
Binary to Decimal conversion
Hello, I am extremely new to Java programming and I need write a program to convert binary numbers to decimal numbers. The input is a string of zeros and ones.
(1001010101011010111001011101010101010101)

All I know is I need to, use a loop to read (charAt()) each digit (0/1 char) in the input string, scanning from right to left, then I need to use the loop to build the required powers of 2. I need to use a conditional statement to deal with 0 and 1 separately, Then I need to Debug using simple input, e.g. 1, 10, 101, and print intermediate values in the loop.

It would be great if someone could help me out with this code as I am very new to this topic
• 12-31-2011, 04:58 PM
JosAH
Re: Binary to Decimal conversion
Can you do it with pencil and paper, with a binary number, say, 1011?

kind regards,

Jos
• 12-31-2011, 05:26 PM
mrashi12
Re: Binary to Decimal conversion
8 4 2 1
1 0 1 1

8+2+1= 11

that is fine, just how to do it with a program please if anyone could help me with that?
• 12-31-2011, 05:32 PM
JosAH
Re: Binary to Decimal conversion
Good; have a look at the top row: it can also be written as, 2*2*2*1, 2*2*1, 2*1, 1; this implies that if you look at the leftmost digit in your binary number (0 or 1), the answer is 0 or 1 too. If more digits follow, you have to multiply your answer by two; in (pseudo) code it look like this:

Code:

```result= 0; for (int i= 0; i < digit.length(); i++) { // walk over all digits   result*= 2; // prepare for another digit, see above   result+= // digit at location i }```
kind regards,

Jos
• 12-31-2011, 08:52 PM
mrashi12
Re: Binary to Decimal conversion
Thank you very much for your help Jos, as I now understand. I hope to see you furthermore as I continue to learn java coding. (y)