Thread: Working with numbers when there's "space" in between them

Hi, I'm working on a program about matrices...for getting the different elements of the matrix I must prompt the user as below:

prompt example: Enter a11, a12, a13, a21, a22, a23, a31, a32, a33: user input example: 1 2 1 2 13 1 4 50 3

now I need to put each number of user input in an element of a 3*3 matrix...if the user input was like 12121314503, I could have used % and / to get each number and assign it to an element of array...or use "parse" methods to change from string to int..... but how can I do such things when space is in between the numbers?!
I really have no clue! any help would be much appreciated!

You can either user String.split() to get a String array containing the individual numbers as Strings, or you can use String.replaceAll() to get rid of the spaces. I'd use the split version.

Hmm, in the OP he had a 13 and a 50, so that would rule out the charAt() solution.

12121314503 is 11 chars so there must be two 2 digit numbers or one 3 digit number to fit into his 3x3 matrix. Or he has to omit remaining digits. Whatever, without him specifying the exact problems we're only guessing (my crystal ball is currently in service).

Originally Posted by Norm

Are you trying to get single decimal digits from the user's input no matter how they were entered?
1 23 and 12 3 and 123 and 1 2 3 would all be considered the same input: 1,2,3

sorry for the delay...and thanks for the responses
all the digits after a space has to be considered one number, for example 1 23 4 7 568 should be considered as 1,23,4,7,568....so the element of a[0][0]=1, a[0][1]=23 and so on.
hope I was clear enough

I think I'm good (for now lol)....I was wondering how to use the method String.split()....did some google and found out it has to be like: StringName.split(" "), with space in between quotation mark!!!
it's a pretty cool method
thank you guys

One hint don't google, but go straight to the API docs: String.split()

looks like I'm actually having a problem
this is the code I wrote so far in order to get a matrix:

 
package matrix.inverse;
 
 
import java.util.*;
 
public class MatrixInverse {
 
 
    public static void main(String[] args) {
 
       System.out.println("Enter a11, a12, a13, a21, a22, a23, a31, a32, a33: ");
 
       String strNumbers = new String();
 
       Scanner x = new Scanner(System.in);
       strNumbers = x.nextLine();
 
       String[] arrStrNumbers = new String[8];
       arrStrNumbers = strNumbers.split(" ");
 
       int[] numbers = new int[8];
 
       for(int i = 0; i<=arrStrNumbers.length ; i++) //converting array of string to array of integers
       {
 
           numbers[i] = Integer.parseInt(arrStrNumbers[i]);
 
       }
 
       //making the matrix 
 
       int[][] matrix = new int[2][2];
 
        numbers[0]=matrix[0][0];
        numbers[1]=matrix[0][1];
        numbers[2]=matrix[0][2];
        numbers[3]=matrix[1][0];
        numbers[4]=matrix[1][1];
        numbers[5]=matrix[1][2];
        numbers[6]=matrix[2][0];
        numbers[7]=matrix[2][1];
        numbers[8]=matrix[2][2];
 
        System.out.println(matrix[2][0]);
 
 
    }
}

I'm trying to test it in the last line( System.out.println(matrix[2][0]); )...but it gives me this error:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 8
at matrix.inverse.MatrixInverse.main(MatrixInverse.ja va:28)
Java Result: 1

what do u think is the problem?

int[] numbers = new int[8]; this is an array of length 8, i.e. the index range is [0,7]. You're trying to access index 8.

GODDAMN IT!!!!!

wait but I changed it to 9, still get the same error, except it's 9 instead of 8 in the error: java.lang.ArrayIndexOutOfBoundsException: 8

changed it, still gives me error!!!!
but found it finally
same thing u said about arrays(confusing length and indexes)...I made a mistake in declaring the matrix array...it should have been a [3][3] instead of [2][2]!!
aaah, I have a looooooong way to go to be a programmer!!lol

Teach your self programming in ten years ?