decimal to binary converter(java)

[yinka90]

Hi. I have a problem with my converter. It works fine. the only problem is that it doesnt convert single digit numbers properly.

public class Main {
 
 
    /**
     * @param args the command line arguments
     */
        public static void main(String[] args){  //throws IOException
        // TO DO codestatic double toDecimal (String s)
           int dec;
           String bin, conv;
                    int a=1;
                    while (a==1)
                    {
           //BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));
           Scanner scan = new Scanner(System.in);
 
           System.out.println("Please enter decimal number to convert to binary" + "\n" + "maximum of 10 digits please");
           bin = scan.next();
           dec = Integer.parseInt(bin);
           int max[] = new int[10];
           int i = 0;
 
           if (dec/2!=0 || dec==1)
           {
              while(dec!=1)
              {
                 max[i]=dec%2;
                 dec = dec/2;
                 i++;
               }
                 max[i]=1;
            }
                    System.out.print("The binary equivalent is "  );
            for (int z=i; z>0; z--)
            {
               System.out.print(max[z]);
            }
 
                   System.out.println("\n" + "Enter 1 for enter another value or 0 to exit:");
                          String reply=scan.next();
                    int b=Integer.parseInt(reply);
                     if(b==1)
                    a=1;
                    else
                    a=0;
}
}
}

[Nepomuk]

Actually, it doesn't work fine. For example, if I enter "10", it will give me "101" as the output. (Same result for "11" by the way.) Now, "101" is 1*2^0 + 0*2^1 + 1*2^2 = 1 + 0 + 4 = 5. The output you want is 1*8 + 0*4 + 1*2 + 0*1 = (1010)binary.

So, go through your code again and try to get it right.

Greetings,
Nepomuk

[chaarmann]

What do you want to achieve with:

if (dec/2!=0 || dec==1) 
{
 ... // convert
}

???
You wrote: I am dividing dec by 2 (for whatever unknown reason) and if the result is not 0, then I convert. That is a complicated way of saying: I skip conversion if the user entered 0 or 1 or -1 as dec! Why did you write that? That doesn't make any sense to me. Then the if-expression goes on with: Or I convert when the user entered dec=1. But you want the opposite: when he entered 1 you want not to convert (but to restart or whatever).
That's quite contradictionary if the user entered "1": first expression says: skip conversion and second says: do it. And if you concatenate that with "or", you alway do it. And as a result this condition prevails: skip conversion if user entered -1 or 0, else do it. I assume that instead you want to skip conversion if the user has entered a 0 or 1, because in this case you don't want to convert, but exit or restart.
So why did you not simply write it in an intuitive and easy way as

if (dec!=0 && dec !=1) convert

?

Is this a program from your teacher that you should debug for learning purposes, or did you write it of your own? If you wrote if of your own, what was in your mind? How did you plan in which way it should work?

By answering these questions you will find the solution to your problem.