Class Project Help! - Multiplication Table - 2D Arrays w/Nested Loops

Ryan Krenz

Hi Everyone.

I am assigned to develop a multiplication table using 2D Arrays and Nested loops. The teacher gave us a starting form/etc, but I just dont know where to start! 2 dimensional arrays really threw me for a loop (no pun intended). Can anyone help get me started?

I have attached the startup form, etc. Here are the class requirements:

A two dimensional array has been declared in the program as: int [ , ] intTable = new int[9,9]; // 9 x 9 table
Students are to develop the method that loads the multiplication table into the array using nested loops. Use intTable.GetLength(0) to go down the table and intTable.GetLength(1) to go across.
Students are to develop the method that displays the array after it has been loaded with the multiplication table using nested loops.
Students are to develop the method that searches the array for all occurrences of the number entered as the search criteria in the textbox. Again, use nested loops.

How shall I start this one?

6 Replies

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edmund durango14y ago
thnkz man!
i will try this in my school....
Ryan Krenz14y ago
I got it: txtTable.AppendText(intTable[r, c].ToString() + " is located in " + r + ", " + c); Thank you for all your help!
Vulpes14y ago
The problem is that you're incrementing r and c too early. Try this instead:

private void btnDisplayArray_Click(object sender, EventArgs e)
{
int r; //row
int c; //column
string strSpace;

txtTable.Clear(); //clear the text box

r = 0;
while (r < 9)
{
c = 0;
while (c < 9)
{
if (intTable[r, c] < 10)
strSpace = " "; //two spaces
else
strSpace = " "; //one space
txtTable.AppendText(strSpace); // insert space

txtTable.AppendText(intTable[r, c].ToString()); //insert result
c++;
}

r++;
txtTable.AppendText("\r\n"); //Move down one line
}
}

As far as the search is concerned, you need to iterate through the array, find any elements which equal the search number and then display the corresponding indices (plus 1) in the textbox.

Here's some code but I've left it to you to figure out how to display the indices in the textbox:

private void btnSearchArray_Click(object sender, EventArgs e)
{
int r; //row
int c; //column
int intSearchNumber;

txtTable.Clear(); //clear the text box

//Enclose in a try-catch to make sure it's a valid number in the textbox
try
{
intSearchNumber = int.Parse(txtSearchNumber.Text);
}
catch (FormatException)
{
MessageBox.Show("Not a valid number, please re-enter");
txtSearchNumber.Focus();
return;
}

// look for number in the array
for (r = 0; r < intTable.GetLength(0); r++)
{
for (c = 0; c < intTable.GetLength(1); c++)
{
if (intSearchNumber == intTable[r, c])
{
// display indices where found // Ryan to do

txtTable.AppendText("\r\n"); //Move down one line
}
}
}

}
Ryan Krenz14y ago
Div        //Modify the nested for loops used above to nested while loops
        private void btnDisplayArray_Click(object sender, EventArgs e)
        {
            int r; //row
            int c; //column
            string strSpace;

            txtTable.Clear(); //clear the text box

            r = 0;
            while (r < 8)
            {
                r++;
                c = 0;
                while (c < 8)
                {
                    c++;
                    if (intTable[r, c] < 10)
                        strSpace = " "; //two spaces
                    else
                        strSpace = " ";   //one space
                    txtTable.AppendText(strSpace); // insert space

                    txtTable.AppendText(intTable[r, c].ToString()); //insert result

                }

                txtTable.AppendText("\r\n"); //Move down one line
            }
        }
Ryan Krenz14y ago
Thank you for your response, this helped greatly. I am very close to creating the "display" part of the array...though I seem to be missing a row and column.

Also, I could use a hint on the "search" function.

Here is my code for the "display", what am I missing?

I also attached my updated project.

THank you!
Vulpes14y ago
I'll do the first part for you (loading the array) but I'd try to do the rest of it yourself otherwise you'll get no benefit from the exercise:

private void btnLoadArray_Click(object sender, EventArgs e)
{
int r; //row
int c; //column
int intResult;

for(r = 0; r < intTable.GetLength(0); r++)
{
for(c = 0; c < intTable.GetLength(1); c++)
{
intResult = (r + 1) * (c + 1);
intTable[r,c] = intResult;
}
}
}