C# - Create a 2D Array and then loop through it

Question

I'm trying to write code that will: Create a multidimensional array, and then loop through all the rows and columns and place a random number between 0 to 9 in that cell.

So for example, if I printed the box/rectangle out it would look something like this:

1 4 6 2 4 1
4 5 6 9 2 1
0 2 3 4 5 9
2 5 6 1 9 4
3 6 7 2 4 6
7 2 2 4 1 4

The code I have (I believe) works OK, however, it only works if I create the array with an equal number of rows and columns (eg, 10x10, 20x20, 15x15) but if I try something like 30x10 I get:

Unhandled Exception: System.IndexOutOfRangeException: Index was outside the boun
ds of the array.
   at ConsoleApplication2.Program.Main(String[] args) in c:\Users\Lloyd\Document
s\Visual Studio 2010\Projects\ConsoleApplication2\ConsoleApplication2\Program.cs
:line 22

Basically, I can't figure out how to create the array with a different number of rows and columns and then loop through it.

Any clues would be appreciated, thanks.

My code:

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        //The width and height of the box.
        const int row = 30;
        const int column = 10;

        static void Main(string[] args)
        {
            int[,] array = new int[row, column];
            Random rand = new Random();

            for (int i = 0; i < column; i++)
            {
                for (int j = 0; j < row; j++)
                {
                    array[i, j] = rand.Next(0, 10);

                }
            }


            for (int i = 0; i < array.GetLength(0); i++)
            {
                for (int j = 0; j < array.GetLength(1); j++)
                {
                    Console.Write(array[i, j].ToString() + " ");
                }
                Console.WriteLine("");
            }
        }
    }
}

Swap row and colum around in your for loops

Sayse
– Sayse

2013-07-23 15:36:13 +00:00
Commented Jul 23, 2013 at 15:36 — Sayse
– Sayse, Commented Jul 23, 2013 at 15:36

Sriram Sakthivel · Accepted Answer · 2013-07-23 15:36:33Z

1

You have reversed in the loop. you allocated 30 rows and 10 columns but looping through 10 rows and 30 columns

Try this

            int[,] array = new int[row, column];
            Random rand = new Random();

            for (int i = 0; i < row; i++)
            {
                for (int j = 0; j < column; j++)
                {
                    array[i, j] = rand.Next(0, 10);

                }
            }

answered Jul 23, 2013 at 15:36

Sriram Sakthivel

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Comments

It'sNotALie. · Accepted Answer · 2013-07-23 15:36:25Z

1

Your for loop is inverted:

for (int i = 0; i < row; i++)
{
    for (int j = 0; j < column; j++)
    {
        array[i, j] = rand.Next(0, 10);

    }
}

answered Jul 23, 2013 at 15:36

It'sNotALie.

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Comments

oGJo · Accepted Answer · 2013-07-23 15:40:38Z

0

I believe you have swapped the row and column indexes when your array is being initialized. Change your

int[,] array = new int[row,  column];

to

int[,] array = new int[column, row];

answered Jul 23, 2013 at 15:40

oGJo

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