2d array with random number

Jonathan Crispe

i had programming exam this morning...i failed...
still i wanna know how to do this.
instruction:
create 2d array [5,5] with random number from 0 to 9... and calculate the column...

        private void button1_Click(object sender, EventArgs e)
        {
            int[,] iArray = new int[5, 5];
            Random rnumber = new Random();
            int inum = rnumber.Next(0, 9);

            for (int x = 0; x < iArray.GetLength(0); x++)
            {
                for (int y = 0; y < iArray.GetLength(1); y++)
                {
                    iArray[x, y] = inum;
                    label1.Text = inum.ToString();
                }
            }
        }
my code showing only 1 random number. instead of 5 by 5 random number...

6 Replies

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Javeed M Shaikh15y ago
Vulpes thanks for correcting the exclusive of the end-point.
Vulpes15y ago
To do it like that, you'd need to adjust your code as follows (I'm assuming the label is big enough to accommodate a table):

int[,] iArray = new int[5, 5];
Random rnumber = new Random();
int inum;
string temp = "";

for (int x = 0; x < iArray.GetLength(0); x++)
{
for (int y = 0; y < iArray.GetLength(1); y++)
{
inum = rnumber.Next(0, 10); // includes 9 but excludes 10
iArray[x, y] = inum;
temp += inum.ToString() + " ";
}
if (x < iArray.GetLength(0) - 1) temp += "\r\n";
}

label1.Text = temp;

When doing something like this it's better to build the string in a temporary variable and then assign the final result to the label's Text property. This avoids the UI having to be updated on each re-assignment.

It would also be more efficient to use a StringBuilder rather than a string when doing a lot of concatenations but no matter :)

Finally, notice that, as your code stood, it was only producing random numbers from 0 to 8 inclusive. When using the Next method you have to remember to make the end-point one more than you need because the random number generated is inclusive of the start-point but exclusive of the end-point.
Jonathan Crispe15y ago
the results of the is: "label + (random numbers)" how to put every 5 numbers in the newline. like writeline" in console application.
Javeed M Shaikh15y ago
ahhhhh...

change...

label1.Text = inum.ToString();

to

label1.Text = label1.Text + " " + inum.ToString();
Jonathan Crispe15y ago
still 1 value showing up...
Javeed M Shaikh15y ago
Hi Jonathan,

you code is assigning it correct but the random should be calculated inside the loop, otherwise it will have only one value.

private void button1_Click(object sender, EventArgs e)
{
int[,] iArray = new int[5, 5];
Random rnumber = new Random();
int inum;

for (int x = 0; x < iArray.GetLength(0); x++)
{
for (int y = 0; y < iArray.GetLength(1); y++)
{
inum = rnumber.Next(0, 9);
iArray[x, y] = inum;
label1.Text = inum.ToString();
}
}
}