[theautokustomizer]

I have wrote this code numerous times, and this is what I have that I think is solid. I have to use a string to input the number, and then calculate the tenth number with an equation...((num1 * 1 + num2 * 2 + num3 * 3 + num4 * 4 + num5 * 5 + num 6* 6 + num7 * 7 + num8 * 8 + num9 * 9) % 11) If the answer to that equation is 10, the tenth digit is an 'X'. Can I take a string apart and do this to the numbers?

import java.util.*;
import java.io.*;

public class ISBN
{
	public static void main(String[] args)
	{
		Scanner console = new Scanner(System.in);
		
		String num;
		int ninthDigit;
		
		System.out.println("Please enter the ISBN number(BE SURE TO PUT SPACES INBETWEEN THE NUMBERS: ");
			num = console.next();

		
		ninthDigit = console.nextInt(0) + console.nextInt(1) + console.nextInt(2) + console.nextInt(3) + console.nextInt(4) +
						console.nextInt(5) + console.nextInt(6) + console.nextInt(7);	
			
		System.out.println("You entered: " + num + " as the ISBN number.");
		
	}
}	

Or am I way off base? ~AUTO~

[nick2price]

There are numerous ways you could seperate your String, most common way problably being using a StringTokenizer. However, this would only be useful if you had some sort of deliminator. If your typing numbers in alltogether, with no spaces, you may want to consider another way.

[pbl]

the Scanner nextInt() method does not have a parameter
I guess you will have to read the whole ISBN as a String and decompose it after using the
Scanner nextLine() method and the String toCharArray() method

[theautokustomizer]

pbl, on 29 Sep, 2009 - 05:05 PM, said:

the Scanner nextInt() method does not have a parameter
I guess you will have to read the whole ISBN as a String and decompose it after using the
Scanner nextLine() method and the String toCharArray() method

That is exactly what I need to do, but I am unsure of how to use that code...can you show me an example, or use my code to help me? TY

[pbl]

String line = console.nextLine();
char[] digit = line.toCharArray();

[theautokustomizer]

pbl, on 29 Sep, 2009 - 05:29 PM, said:

String line = console.nextLine();
char[] digit = line.toCharArray();

Okay, this is what I have....

import java.util.*;
import java.io.*;

public class ISBN
{
	public static void main(String[] args)
	{
		Scanner console = new Scanner(System.in);
		
		String num;
		int tenthDigit;
		
		System.out.println("Please enter the ISBN number(BE SURE TO PUT SPACES INBETWEEN THE NUMBERS: ");
			num = console.nextLine();
				
		tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
							(num[7] * 8) + (num[8] * 9) % 11);
							
			if (tenthDigit == 10)
			{
				tenthDigit = 'X';
			}
			
			else if (tenthDigit != 10)
			{
				tenthDigit = tenthDigit;
			}		
							
			
		System.out.println("The tenth digit is: " + tenthDigit);
		
	}
}	

And these are my errors...


----jGRASP exec: javac -g C:\Users\Christopher\Documents\ISBN.java

ISBN.java:22: array required, but java.lang.String found
tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
^
ISBN.java:22: array required, but java.lang.String found
tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
^
ISBN.java:22: array required, but java.lang.String found
tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
^
ISBN.java:22: array required, but java.lang.String found
tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
^
ISBN.java:22: array required, but java.lang.String found
tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
^
ISBN.java:22: array required, but java.lang.String found
tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
^
ISBN.java:23: array required, but java.lang.String found
(num[7] * 8) + (num[8] * 9) % 11);
^
ISBN.java:23: array required, but java.lang.String found
(num[7] * 8) + (num[8] * 9) % 11);
^
8 errors

----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.

Where would I put the other statement that you gave me? And what is going on with my compiler?

[pbl]

Aie ! Aie ! Aie !
You are really lost num is a String you cannot num(0) or num(1)

// read a line as a String with the scanner
String line = console.nextLine();
// translate thius line into a char array
char[] digit = line.toCharArray();
// make an array of it to work with int
int[] num = new int[digit.length];
// convert char (which are ASCII character into int)
for(int i = 0; i < digit.length; i++) {
   num[i] = (int) digit[i];	 // cast char to int
   num[i] -= (int) '0';		 // translate from ASCII to int
}

// now you can play with num[0], num[1], ......

[theautokustomizer]

pbl, on 29 Sep, 2009 - 05:48 PM, said:

Aie ! Aie ! Aie !
You are really lost num is a String you cannot num(0) or num(1)

// read a line as a String with the scanner
String line = console.nextLine();
// translate thius line into a char array
char[] digit = line.toCharArray();
// make an array of it to work with int
int[] num = new int[digit.length];
// convert char (which are ASCII character into int)
for(int i = 0; i < digit.length; i++) {
   num[i] = (int) digit[i];	 // cast char to int
   num[i] -= (int) '0';		 // translate from ASCII to int
}

// now you can play with num[0], num[1], ......

Thank you very much...I just have a few questions though. What does the '-=' do? Also, my math is screwy on this... I want to learn this, that is why I am asking...I am not trying to ignorant, just want to understand this inside and out. TY ~AUTO~

This is what I have ....

import java.util.*;
import java.io.*;

public class ISBN
{
	public static void main(String[] args)
	{
		Scanner console = new Scanner(System.in);
		
		System.out.println("Please enter the ISBN number: ");
			String line = console.nextLine();
			
		char[] digit = line.toCharArray();
		
		int[] num = new int[digit.length];

		for(int i = 0; i < digit.length; i++)
		{
			num[i] = (int) digit[i];
			num[i] -= (int) '0'; 
		}

	int tenthDigit = ((num[0] * 1) + (num[1] * 2) + (num[2] * 3) + (num[4] * 5) + (num[5] * 6) + (num[6] * 7) +
							(num[7] * 8) + (num[8] * 9) % 11);
							
		if (tenthDigit == 10)
		{
			tenthDigit = 'X';
		}
			
		else if (tenthDigit != 10)
		{
			tenthDigit = tenthDigit;
		}		
							
			
		System.out.println("The tenth digit is: " + tenthDigit);
		
	}
}

It compiles great... Here is my compiler output....

----jGRASP exec: javac -g C:\Users\Christopher\Documents\ISBN.java


----jGRASP: operation complete.

And here is my program output....


----jGRASP exec: java ISBN

Please enter the ISBN number:
013604258
The tenth digit is: 95

----jGRASP: operation complete.

I don't know what is going on with it, but it needs to read like a real ISBN. It needs to have a single tenth digit or the 'X', I know that I can use the printf and the %.2f for decimal places, but is there something that I can use predecimal point? Or is my math just wrong? Am I not seeing something? TY again for all of the help!!!!

[pbl]

		if (tenthDigit == 10)
		{
			tenthDigit = 'X';
		}
			
		else if (tenthDigit != 10)	   // else if(thenthDigit == 10) is surely thenthDigit != 10 kind a useless if here
		{										// 
			tenthDigit = tenthDigit;	 // unless I really miss the point this is also useless
		}										// so the 4 last lines are really useless

[theautokustomizer]

pbl, on 29 Sep, 2009 - 06:40 PM, said:

		if (tenthDigit == 10)
		{
			tenthDigit = 'X';
		}
			
		else if (tenthDigit != 10)	   // else if(thenthDigit == 10) is surely thenthDigit != 10 kind a useless if here
		{										// 
			tenthDigit = tenthDigit;	 // unless I really miss the point this is also useless
		}										// so the 4 last lines are really useless

Well I have never been told that I have underbuilt anything, motors, bathrooms, sheds, etc,...so I figured if it was in there, it was there. It is all figured out now,(BIG THANKS TO pbl), I got my calculations messed up because I missed a set of parens....my fault, lol. But, I know that the -= is the subtraction assignment right to left, but I don't see how it plays in this with the '0'...can you further explain please...

[pbl]

  if (tenthDigit == 10)
		{
			tenthDigit = 'X';
		}

thenthDigit is an int
if you assign it 'X' it will take the ASCII value of character 'X'
you can print it as a char thow

don't really understand your "algorithm" thow

assume that you ISBN first digits are 11111111

1 * 1 + 1 * 2 + 1* 3 * 1 * 4... is surely higher than 10
how can you expect the sum to be 10 ?

oups... missed the % 11 sorry

First use a loop

int total = 0;
for(int i = 0; i < 9; i++)
   total += (num[i] * (i+1));

int mod = total % 11;
char lastDigit;
if(mod == 10)
   lastDigit = 'X';
else
   lastDigit = '0' + mod;