Official Java Thread

**Zero** · 13-11-2008, 21:56

Any value greater than 255? Well, I tried 266 and the program gives me the value 100001010 when I run it (as expected)...?

Hmm...I see. So that would probably used the String.charAt() method?

Then I might need a loop...something like...

i = 0;

While(i<=args.length)

i++;

Thats to "walk along" the length of string I suppose...I'll see what I can do.

**vertigo** · 13-11-2008, 22:10

i need help with my program if any1s got a chance

ima upload the java file and c if u can get it to work prop

im doin a noughts and crosses game, and am tryin to play against the computer

im having a problem in making the computer make its move after ive made mine

[ATTACHMENT REMOVED UPON REQUEST]

**Evil_Genious** · 13-11-2008, 22:57

I know this is very ugly dirty code... But please bear in mind, I'm new to Java myself and I've been up since 5am LOL.. Anyway... Here's what I came up with, it works... There's no error checking so if you don't send in valid binary and not letters, it doesn't check... Have a look at it, see what you think, maybe it'll jog your train of thought....

Code:

	public static int binToDec (String b)
	{
		// Declarations
		int string_length = 0;
		int loop_control = 0;
		int inc_b = 1;
		char toconvert = 'a';
		int converted = 0;
		int return_value = 0;
		
		// Initialise
		string_length = b.length();
		loop_control = string_length;
		
		// Process binary data		
		while (loop_control > 0)
		{
			toconvert = b.charAt((loop_control - 1));
			converted = Integer.parseInt(Character.toString(toconvert));
			
			return_value = return_value + (converted * inc_b);
			
			inc_b = inc_b * 2;
			loop_control = loop_control - 1;
									
		}		
		
		// Return value
		return return_value;
		
	}

Call it with that main thing you had...

**Zero** · 13-11-2008, 23:22

Originally Posted by vertigo

i need help with my program if any1s got a chance

ima upload the java file and c if u can get it to work prop

im doin a noughts and crosses game, and am tryin to play against the computer

im having a problem in making the computer make its move after ive made mine

Bloody hell, thats way to advanced for me...and probably EG too! lol unless he's overtaken me...!

**Evil_Genious** · 13-11-2008, 23:23

LOL I know better than open a .zip file with code in it.......

**Evil_Genious** · 13-11-2008, 23:30

I opened it anyway, I haven't done Swing. So can't tell you.... Soz.... And would need to run it to see what it does... LOL and I don't even know how to do that...

**vertigo** · 13-11-2008, 23:41

open it up with any editor program

and run it off from dos

using the javac - compile and java to run

if u guys dnt no how to do it nvm then, i jus thought id give it a shot

**Zero** · 14-11-2008, 00:01

Originally Posted by Evil_Genious

I know this is very ugly dirty code... But please bear in mind, I'm new to Java myself and I've been up since 5am LOL.. Anyway... Here's what I came up with, it works... There's no error checking so if you don't send in valid binary and not letters, it doesn't check... Have a look at it, see what you think, maybe it'll jog your train of thought....

Code:

 
    public static int binToDec (String b)
    {
        // Declarations
        int string_length = 0;
        int loop_control = 0;
        int inc_b = 1;
        char toconvert = 'a';
        int converted = 0;
        int return_value = 0;
 
        // Initialise
        string_length = b.length();
        loop_control = string_length;
 
        // Process binary data        
        while (loop_control > 0)
        {
            toconvert = b.charAt((loop_control - 1));
            converted = Integer.parseInt(Character.toString(toconvert));
 
            return_value = return_value + (converted * inc_b);
 
            inc_b = inc_b * 2;
            loop_control = loop_control - 1;
 
        }        
 
        // Return value
        return return_value;
 
    }

Call it with that main thing you had...

LOL...the joy's of working in CSci eh...5AM starts!

I've desk-checked the loop and I understand it...its given me an idea...I think I'd try to implement it as a for loop and I've got a vague idea how to do that...

I'm a bit confused why you assigned "a" to the variable toConvert of type char though...at the declarations section?

**Evil_Genious** · 14-11-2008, 00:11

Code:

C:\>cd C:\oxo2

C:\>javac oxo2.java
Note: oxo2.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

C:\>javac -Xlint oxo2.java
oxo2.java:112: warning: [unchecked] unchecked call to add(E) as a member of the
raw type java.util.ArrayList
                    al.add(box);                                          // add
s the box to the arraylist
                          ^
1 warning

Doesn't compile. I don't know enough about Java's libraries to see what the problem is... Maybe that was the problem you're lookin to solve.....

**Evil_Genious** · 14-11-2008, 00:13

Originally Posted by Zero

I'm a bit confused why you assigned "a" to the variable toConvert of type char though...at the declarations section?

No reason, just for the sake of initialising it to a known value. Until I set it to something I don't know whats in there, could be garbage... So set it to something when you declare it, just to ensure that something that was in memory at the time isn't in there. Which could be anything...

**Zero** · 14-11-2008, 00:33

Oh ok...Hmm...I was reading that when you initialise the variable...without the value...then java uses the default value?

Thats only in Java I think...

The default for boolean is False, default for int is 0, default for string is null and default for float is 0.0F etc...

Well, my brains not functioning anymore now..so I think I'll give it another shot 2mo and then show what I've got in here..

**vertigo** · 14-11-2008, 00:47

i fixed my game and it works perfectly

**Zero** · 14-11-2008, 18:07

Thanks for the sticky mr/mrs mod!

Right, take a look at this;

Code:

public static int binToDec (String b)
 
{
  
//this method uses a "for" loop

int result = 0;
  
    for (int i = 0; i < b.length(); i++)
    
    {

    result = (result * 2) + (b.charAt(i) - '0');

    }
  
  return result;
 
}
 
//end of method

I think that more or less wraps it up...

I haven't really tested it fully and there isn't anything for error/exception handling, so its fairly basic. It still gets the job done though!

**Zero** · 14-11-2008, 18:15

Note: I didn't write that code.

I can't seem to follow the logic however... the length of the string determines how many time the method loops, and the "b.charAt" extracts each character from the string... and then minuses zero from it? How does that work? And surely in binary each digit has a certain weight (1,2,4,8,16,32,64,128, etc.)...?
Is that sorted out using the expression "result = result * 2" ?

**Evil_Genious** · 14-11-2008, 20:49

Looks as if someone is offsetting the ASCII decimal of 0 from whatever number it is to calculate the number that is in the string.

Ascii Table - ASCII character codes and html, octal, hex and decimal chart conversion

So if you have 3 the ASCII decimal of 3 is -> 51.

And 0 in ASCII decimal is -> 48

so: the calculation: '3' - '0' is really doing:

51 - 48 = 3

Yeah it make sense LOLL.... Far simpler than the tripe I wrote....