Programming Forums > Application Development > Java

gam3r · Nov 8th, 2007, 10:14 AM

I know it is frustrating trying to help someone like me but i'm trying so hard, i have limited java experience, just a beginner and i am tearing my hair out. I just don't know what to do.

ReggaetonKing · Nov 8th, 2007, 11:50 AM

OMG! Just post your entire code that you have and the error messages you get. What is so confusing about my solution?

Infinite Recursion · Nov 8th, 2007, 3:56 PM

ReggaetonKing's code works fine. Make sure you didn't copy-and-paste it into the middle of another one of your functions and be sure you are calling his function with proper parameters. If you are still confused, definitely post your code and errors that you receive. Oh, btw... his code is in fact using recursion... what exactly were you expecting?

gam3r · Nov 9th, 2007, 6:02 AM

Ah sorry my bad i'm an idiot! I didn't read through it properly gahhhh! Sorry guys, im gonna go and have a tinker around and will get back to you.

gam3r · Nov 11th, 2007, 3:47 PM

Hey guys.

I have managed to get my code to work now, but there is one slight problem. The binary output is backwards i.e it reads from left to right instead of right to left like binary should so 25 is outputed as 100110 instead of 011001.

How do i get it to output in reverse order?

Here is my code:

(Toggle Plain Text)

public static String decTobin (int n){
	if (n==0){
		return "0";
	}
	if (n%2==0){
		return "0" + decTobin(n/2);
	}
	else {
		return "1" + decTobin(n/2); 
		}


}

DaWei · Nov 11th, 2007, 5:00 PM

Reverse the returned string, or do it another way.

gam3r · Nov 13th, 2007, 1:11 PM

Quote:

Originally Posted by DaWei

Reverse the returned string, or do it another way.

How can i do that? Can you give me any hints...?

My code actually doesn't save the output into a string, instead it just prints the answer out on the screen on the fly so how would i do it, would i have to implement a string to reverse it?

thanks

ReggaetonKing · Nov 13th, 2007, 1:23 PM

[DELETED] *not even worth it.

DaWei · Nov 13th, 2007, 1:24 PM

Yes, you could put it into a string and reverse it. That's accomplished by swapping the first and last characters, then the second and second-to-last characters, then the third and (you get the picture) until the swap reaches the middle.

Alternatively, you could do it another way. Consider your method: you are using the modulus operator (actually, the remainder operator) to test the least significant bit. You are then dividing by 2 to shift the number right, then testing the new LSB.

You COULD set up to test beginning with the MSB and work your way down to the LSB.

Harakim · Nov 14th, 2007, 2:24 AM

Alternatively, you could do this depending on your specs:

(Toggle Plain Text)

	public static String decToBin( int n )
	{
		if (n==0)
			return "";

		if (n%2==0)
			return decToBin(n/2) + "0";
		else
			return decToBin(n/2) + "1";
	}

Nov 8th, 2007, 10:14 AM	#11
gam3r Newbie Join Date: Jun 2005 Location: London, England Posts: 24 Rep Power: 0	Re: Decimal to binary help I know it is frustrating trying to help someone like me but i'm trying so hard, i have limited java experience, just a beginner and i am tearing my hair out. I just don't know what to do. __________________ biggest NOOB ever :P

Nov 8th, 2007, 11:50 AM	#12
ReggaetonKing Sexy Programmer Join Date: Nov 2005 Location: New Jersey Posts: 891 Rep Power: 3	Re: Decimal to binary help OMG! Just post your entire code that you have and the error messages you get. What is so confusing about my solution? __________________ I would love to change the world, but they won't give me the source code!

Nov 8th, 2007, 3:56 PM	#13
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,453 Rep Power: 7	Re: Decimal to binary help ReggaetonKing's code works fine. Make sure you didn't copy-and-paste it into the middle of another one of your functions and be sure you are calling his function with proper parameters. If you are still confused, definitely post your code and errors that you receive. Oh, btw... his code is in fact using recursion... what exactly were you expecting? __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

Nov 9th, 2007, 6:02 AM	#14
gam3r Newbie Join Date: Jun 2005 Location: London, England Posts: 24 Rep Power: 0	Re: Decimal to binary help Ah sorry my bad i'm an idiot! I didn't read through it properly gahhhh! Sorry guys, im gonna go and have a tinker around and will get back to you. __________________ biggest NOOB ever :P

Nov 11th, 2007, 3:47 PM	#15
gam3r Newbie Join Date: Jun 2005 Location: London, England Posts: 24 Rep Power: 0	Re: Decimal to binary help Hey guys. I have managed to get my code to work now, but there is one slight problem. The binary output is backwards i.e it reads from left to right instead of right to left like binary should so 25 is outputed as 100110 instead of 011001. How do i get it to output in reverse order? Here is my code: (Toggle Plain Text) public static String decTobin (int n){ if (n==0){ return "0"; } if (n%2==0){ return "0" + decTobin(n/2); } else { return "1" + decTobin(n/2); } } public static String decTobin (int n){ if (n==0){ return "0"; } if (n%2==0){ return "0" + decTobin(n/2); } else { return "1" + decTobin(n/2); } } __________________ biggest NOOB ever :P

Nov 11th, 2007, 5:00 PM	#16
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Re: Decimal to binary help Reverse the returned string, or do it another way. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Nov 13th, 2007, 1:23 PM	#18
ReggaetonKing Sexy Programmer Join Date: Nov 2005 Location: New Jersey Posts: 891 Rep Power: 3	Re: Decimal to binary help [DELETED] *not even worth it. __________________ I would love to change the world, but they won't give me the source code!

Nov 13th, 2007, 1:24 PM	#19
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Re: Decimal to binary help Yes, you could put it into a string and reverse it. That's accomplished by swapping the first and last characters, then the second and second-to-last characters, then the third and (you get the picture) until the swap reaches the middle. Alternatively, you could do it another way. Consider your method: you are using the modulus operator (actually, the remainder operator) to test the least significant bit. You are then dividing by 2 to shift the number right, then testing the new LSB. You COULD set up to test beginning with the MSB and work your way down to the LSB. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Nov 14th, 2007, 2:24 AM	#20
Harakim Hobbyist Programmer Join Date: May 2006 Location: West Jordan, Utah, United States Posts: 176 Rep Power: 3	Re: Decimal to binary help Alternatively, you could do this depending on your specs: (Toggle Plain Text) public static String decToBin( int n ) { if (n==0) return ""; if (n%2==0) return decToBin(n/2) + "0"; else return decToBin(n/2) + "1"; } public static String decToBin( int n ) { if (n==0) return ""; if (n%2==0) return decToBin(n/2) + "0"; else return decToBin(n/2) + "1"; }

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Programming Forums > Application Development > Java

Decimal to binary help