Unable to clear array and string

Question

I have a following program, it takes strings from 4 textboxes and puts them into array and displays the message(created from the array) after user clicks on btnOK. I have a button called btnClear which if clicked should clear both the message string and array but it's not doing it and I'm not quite sure why, can someone have a look and advise.

string[,] namesTable = new string[10, 4];
int row = 0;
string message = "";

private void btnOK_Click_1(object sender, EventArgs e)
{

  namesTable[row, 0] = txtFirstName.Text;
  namesTable[row, 1] = txtSurname.Text;
  namesTable[row, 2] = txtPosition.Text;
  namesTable[row, 3] = txtComment.Text;
  row++;

  message = "Name.\tSurname\tPosition\tComment\n";
  for (int i = 0; i < namesTable.GetLength(0); i++)
  {
    if (namesTable[i, 0] != null)
    {
      for (int j = 0; j < namesTable.GetLength(1); j++)
      {
        message += namesTable[i, j] + "\t";
      }
      message += "\n";
    }
  }

  MessageBox.Show(message, "Names Table");
}

private void btnClear_Click_1(object sender, EventArgs e)
{
    Array.Clear(namesTable, 0, 4);
    message = "";
}

If you need more info please let me know.

fardjad · Accepted Answer · 2011-05-14 13:55:51Z

1

The range of cleared elements wrap from row to row in a multi-dimensional array therefore You should use:

Array.Clear(namesTable, 0, 40);
//                      ^  ^
//                      |  |_The number of elements to clear.
//                      |
//                      |____The starting index of the range of elements to clear.

edited May 14, 2011 at 13:55

answered May 14, 2011 at 13:49

fardjad

20.5k6 gold badges55 silver badges68 bronze badges

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

2 Comments

Blücher Over a year ago

@fadjad Can you explain, why when I have it set to 4 and do following: 1) enter 4 values, click OK, 2)click OK again 3)click Clear 4) click OK again Message box still shows second row and third?

fardjad Over a year ago

Because in your code: Array.Clear(namesTable, 0, 4); only sets namesTable[0, 1] through namesTable[0, 4] zero.

Juan Carlos Velez · Accepted Answer · 2011-05-14 13:59:36Z

0

If you want to clear all your data, so reinitialize all:

private void btnClear_Click_1(object sender, EventArgs e)
{
    this.namesTable = new string[10, 4];
    this.row = 0;
    this.message = "";
}

answered May 14, 2011 at 13:59

Juan Carlos Velez

2,9402 gold badges36 silver badges50 bronze badges

Comments

driis · Accepted Answer · 2011-05-14 14:17:06Z

0

You are clearing 4 values in the array from index 0. However, your insert code inserts at the row index. This is likely to be your problem. What is the value of row ?

To clear everyting in the array, simply do:

namesTable = new string[10, 4];
row = 0;

edited May 14, 2011 at 14:17

answered May 14, 2011 at 13:47

driis

165k46 gold badges272 silver badges345 bronze badges

4 Comments

Blücher Over a year ago

row is automaticaly calculated - incremented when new "row" of data is created

driis Over a year ago

Do you want to re-initalize all rows, or just the current one ? Under all circumstances, you will want to clear the correct portion of your array. If you need to clear everything just new a new array and set row to 0.

Blücher Over a year ago

by "new a new array" do you mean clear existing one or something else?

Blücher Over a year ago

Thank you it works too but I can only select one correct answer.

Collectives™ on Stack Overflow

Unable to clear array and string

3 Answers 3

2 Comments

Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related