Strange system.out

[Brian Pianczk]

The only way I know how to have this looked at is to post the whole code and the returned results.
I have a feeling it has something with reading the array from right to left and then trying to display it left to right with another array.

  import java.util.Scanner;
public class test2 
{

	private static char [] plus (char [] a, char [] b)
	{
		char c = '0'; // sets carry to 0 from any previous line.
		char [] result = new char [8];
		for (int i = a.length -1; i<0; i++) // read the two arrays from right to left
		{
			if (a[i] == '0' && b[i] == '0') // All of these if statements are suppose to go through the truth 
			{								// table for addition. Can't get it to work just yet. result displays boxes.
				if (c == '0')
				{
					result [i] = '0';
					c = '0';
				}
				if (c == '1')
				{
					result [i] = '1';
					c = 'o';
				}
			}
			else if (a[i] == '0' && b[i] == '1')
			{
				if (c == '0')
				{
					result [i] = '1';
					c = '0';
				}
				if (c == '1')
				{
					result [i] =0;
					c ='1';
				}
			}
			else if (a[i] == '1' && b[i] == '0')
			{
				if (c == 'o')
				{
					result [i] = '1';
					c = '0';
				}
				if (c == '1')
				{
					result [i] =0;
					c ='1';
				}
			}
			else if (a[i] == 1 && b[i] == 1)
			{
				if (c == '0')
				{
					result[i] = 0;
					c = '1';
				}
				if (c == '1')
				{
					result[i] = 1;
					c ='1';
				}
			}
			
		}
		return result; // result should fill from left to right
}

	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		String A1, B1;
		System.out.print("Enter an 8 bit binary string to be called A:"); // String A1
		A1 = scan.nextLine();
		char [] a = A1.toCharArray();
		for (int i = 0; i<a.length; i++) 	// array to check if a 0 or 1 was used
			if (!(a[i] == '0' || a[i] == '1'))
			{
				System.out.print("Error in A, only 0 or 1 are acceptable entries.");
				System.exit(0);
			}
	
		System.out.print("Enter an 8 bit binary string to be called B:"); // String B1
		B1 = scan.nextLine();
		char [] b = B1.toCharArray();
		for (int i = 0; i<b.length; i++)
			if (!(b[i] == '0' || b[i] == '1'))
			{
				System.out.print("Error in B, only 0 or 1 are acceptable entries.");
				System.exit(0);
			}	
		System.out.println("A plus B = " +String.valueOf(test2.plus(a,b)));// Right now displays gibberish. 1/29/09
	}
}	
		
		  

My returned statement is: A plus B = (wont display what it dsiplays on the console, which are 8 boxes)

[Justin Fox]

try this code instead, and i'll let you know what the errors where....

  import java.util.Scanner;   
public class test2    
{   
  
    public static char [] plus (char [] a, char [] b)   
    {   System.out.println("got here");
        char c = '0'; // sets carry to 0 from any previous line.   
        char [] result = new char [8];   
        for (int i = a.length -1; i>0; i--) // read the two arrays from right to left   
        {  
		System.out.println(a[i]);
                System.out.println(i);
 
            if (a[i] == '0' && b[i] == '0') // All of these if statements are suppose to go through the truth    
            {                               // table for addition. Can't get it to work just yet. result displays boxes.   
                if (c == '0')   
                {   
                    result [i] = '0';   
                    c = '0';   
                }   
                if (c == '1')   
                {   
                    result [i] = '1';   
                    c = '0';   
                }   
            }   
            else if (a[i] == '0' && b[i] == '1')   
            {   
                if (c == '0')   
                {   
                    result [i] = '1';   
                    c = '0';   
                }   
                if (c == '1')   
                {   
                    result [i] = '0';   
                    c ='1';   
                }   
            }   
            else if (a[i] == '1' && b[i] == '0')   
            {   
                if (c == '0')   
                {   
                    result [i] = '1';   
                    c = '0';   
                }   
                if (c == '1')   
                {   
                    result [i] = '0';   
                    c ='1';   
                }   
            }   
            else if (a[i] == 1 && b[i] == 1)   
            {   
                if (c == '0')   
                {   
                    result[i] = '0';   
                    c = '1';   
                }   
                if (c == '1')   
                {   
                    result[i] = '1';   
                    c ='1';   
                }   
            }   
               
        }   
        return result; // result should fill from left to right   
}   
  
    public static void main(String[] args)   
    {   
        Scanner scan = new Scanner(System.in);   
        String A1, B1;   
        System.out.print("Enter an 8 bit binary string to be called A:"); // String A1   
        A1 = scan.nextLine();   
        char [] a = A1.toCharArray();   
        for (int i = 0; i<a.length; i++)     // array to check if a 0 or 1 was used   
            if (!(a[i] == '0' || a[i] == '1'))   
            {   
                System.out.print("Error in A, only 0 or 1 are acceptable entries.");   
                System.exit(0);   
            }   
       
        System.out.print("Enter an 8 bit binary string to be called B:"); // String B1   
        B1 = scan.nextLine();   
        char [] b = B1.toCharArray();   
        for (int i = 0; i><b.length; i++)   
            if (!(b[i] == '0' || b[i] == '1'))   
            {   
                System.out.print("Error in B, only 0 or 1 are acceptable entries.");   
                System.exit(0);   
            }      
        System.out.println("A plus B = ");// Right now displays gibberish. 1/29/09 
        char [] value = test2.plus(a,b);
        for(int k = 0; k< value.length; k++)  
        { System.out.print(value[k]); }
    }   
}  

ok first, your for loop in the plus method was like this...

for( int i = a.length -1; i < 0; i ++)...

obvious and easy to make mistake, but if i = the length of your array -1
then i will always be > 0 so the conditional 'i < 0' in the for loop made the
loop never execute, and also the 'i++' needs to be 'i--' going from right to left...

next was that some of your '0' and 'o' were getting mixed up, and also you had something
like: 'result[i] = 1' instead of 'result[i] = '1'', it is a character array, not integer.

and finally in the main method, you were calling something like....

System.out.println( String.valueOf(test2.plus(a,b)));

If you look at the return type of plus, it is a array, so you would need to set that return
variable to an instance of char[] and then loop through and print it out.

you can comment out the "got here" and the other two println comments, thats just how
i debugged it.

Hope this helps ya out,

Justin

[Justin Fox]

I put in : 00000001 and 00000010 and got 00000011
1 + 2 = 3;

Thats the only test i ran, you might want to test larger number to
see if they come out right.

Justin

[Brian Pianczk]

Justin Fox wrote:I put in : 00000001 and 00000010 and got 00000011
1 + 2 = 3;

Thats the only test i ran, you might want to test larger number to
see if they come out right.

Justin

Yeah, Justin I looked again , and in my haste didnt notice I cut and pasted my final code together, from my tests wrong, I am sorry for this.

I appreciate your going through and looking at it. I didnt notice the looping was wrong.

Thanks

[Justin Fox]

No problem,

I enjoy helping when I can lol.

Justin