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Help with code

 
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Help with code
dwd3773
17 Mar, 2008 - 03:55 PM
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Ok this program is supposed to take number 1-12 and create a 2 dimensional array as follows:
{1,2,3,4},
{5,6,7,8},
{9,10,11,12},

and display the output as 1,5,9,2,6,10,3,7,11,4,8,12.

I need it to display the number in that orde but the program I crated displays them in regular numerical order. Heres my code so far:
CODE

public class Assign8
{
    public static void main(String[] args)
    {
        int [][] inTar =
        {
            {1,2,3,4},
            {5,6,7,8},
            {9,10,11,12},
        };

        for (int row = 0; row < inTar.length; row++)
        {
            for(int col= 0; col < inTar[row].length; col++)
            {
                System.out.println(inTar[row][col]);
            }
        }
    }
}
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GWatt
RE: Help With Code
17 Mar, 2008 - 04:10 PM
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Do this inside your for loop:
System.out.println(inTar[col][row] );
Just reverse the row and col variables.
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dwd3773
RE: Help With Code
17 Mar, 2008 - 04:48 PM
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I tried that and everything compiles correctly, but when I run the application it displays the first 3 numbers 1,5,9 correctly, but then I get an error as follows:
exception in thread "main" java.lang.arrayindexoutofboundsexception:3
at assign8.main<assign8.java:17>
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GWatt
RE: Help With Code
17 Mar, 2008 - 05:05 PM
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Then try this:
java

for (int col = 0; col < inTar[0].length; col++)
    for (int row = 0; row < inTar.length; row++)
        System.out.print(inTar[row][col] );


I just reverse the inner and outer for loops.
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dwd3773
RE: Help With Code
17 Mar, 2008 - 05:19 PM
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Thank you, that worked perfectly. I would have never thought about adding the zero there.
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Steven Smith
RE: Help With Code
17 Mar, 2008 - 05:38 PM
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Your error was in creating an out of bounds reference through inTar[col].length.

Say you have 4 rows and 3 columns. The length of the column is four. The length of column 1 is four, the length of 2 is four, etc... This is your logic. Unfortunately, you asked the program to return the length of column 4... but you only have 3 columns.

Next time, break out your maxRow, and maxCol references outside your for loop. They don't need to be reevaluated every loop, it wastes resources. It also forces you to link about your bounds better ahead of time.

This post has been edited by Steven Smith: 17 Mar, 2008 - 05:39 PM
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