C# Passing and returning a multidimensional array

Question

I have a 2D array, that I fill randomly with numbers. The code I have for this works fine, however, to organise my code better I'm wanting to put the "fill it randomly with numbers" part into a method.

The array is created from the Main() method, as I plan on passing and returning the array to/from other methods that will manipulate it. I then tried to write the method for filling the array, but I'm unsure how to either pass a multidimensional array, or return one either. According to MSDN I need to use an "out" rather than a return.

This is what I've tried so far:

    static void Main(string[] args)
    {
            int rows = 30;
            int columns = 80;



            int[,] ProcArea = new int[rows, columns];

            RandomFill(ProcArea[], rows, columns);

    }

    public static void RandomFill(out int[,] array, int rows, int columns)
    {

        array = new int[rows, columns];


        Random rand = new Random();
        //Fill randomly
        for (int r = 0; r < rows; r++)
        {
            for (int c = 0; c < columns; c++)
            {
                if (rand.NextDouble() < 0.55)
                {
                array[r, c] = 1;
            }
            else
            {
                array[r, c] = 0;
            }
        }
    }

These are the errors I have:

"The best overloaded method match for 'ProcGen.Program.RandomFill(out int[*,*], int, int)' has some invalid arguments"
"Argument 1: cannot convert from 'int' to 'out int[*,*]'"

What am I doing wrong, and what can I do to fix these errors? Also, am I right in thinking, because I'm using "out" that all I need to do is:

RandomFill(ProcArea[], rows, columns);

instead of?:

ProcArea = RandomFill(ProcArea[], rows, columns);

Is there a proper way of calling the method?

Patman · Accepted Answer · 2019-12-10 19:51:38Z

7

There is no need of an out parameter in your code.

Arrays are passed by reference until, in the method, you initialise it with a new reference.

So, in your method, if you don't initialise it with a new reference, then you can go without using the out parameter and values will be reflected in the original array -

public static void RandomFill(int[,] array, int rows, int columns)
{

    array = new int[rows, columns]; // <--- Remove this line since this array
                                    // is already initialised prior of calling
                                    // this method.
    .........
}

edited Dec 10, 2019 at 19:51

Patman

418 bronze badges

answered Jul 27, 2013 at 10:32

Rohit Vats

81.5k13 gold badges170 silver badges193 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Tsahi Asher Over a year ago

The reason you shouldn't new the array is because this will overwrite the reference passed to the method, and the calling site won't see this new reference.

user3094403 · Accepted Answer · 2013-07-27 10:26:09Z

2

Try:

RandomFill(out ProcArea, rows, columns);

answered Jul 27, 2013 at 10:26

user3094403

6,39011 gold badges50 silver badges56 bronze badges

Comments

juhan_h · Accepted Answer · 2013-07-27 10:40:33Z

2

Out parameters need to be explicitly specified as out in the caller's side as well:

RandomFill(out ProcArea[], rows, columns);

edited Jul 27, 2013 at 10:40

answered Jul 27, 2013 at 10:26

juhan_h

4,0214 gold badges31 silver badges35 bronze badges

Comments

Mohammad Khoirul Effendi · Accepted Answer · 2015-09-05 16:38:11Z

Try it...it works :)

using System;
class system
{
    static void Main(string[] args)
    {
            int rows = 5;
            int columns = 5;


            int[,] ProcArea = new int[rows, columns];

            RandomFill(out ProcArea, rows, columns);

        // display new matrix in 5x5 form
            int i, j;
            for (i = 0; i < rows; i++)
            {
                for (j = 0; j < columns; j++)
                    Console.Write("{0}\t", ProcArea[i, j]);
                Console.WriteLine();
            }
            Console.ReadKey();

    }

    public static void RandomFill(out int[,] array, int rows, int columns)
    {

        array = new int[rows, columns];


        Random rand = new Random();
        //Fill randomly
        for (int r = 0; r < rows; r++)
        {
            for (int c = 0; c < columns; c++)
            {
                if (rand.NextDouble() < 0.55)
                {
                    array[r, c] = 1;
                }
                else
                {
                    array[r, c] = 0;
                }
            }
        }
    }
}

Collectives™ on Stack Overflow

C# Passing and returning a multidimensional array

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related