get value from dynamic Textbox

Question

I hava some arrays to save my controls. when call a function initialize arrays and save in arrays my controls.

Code:

private Label[] lblName;
    private TextBox[] txtName;
    private Label[] lblSurname;
    private TextBox[] txtSurname;
    private Label[] lblInstitution;
    private TextBox[] txtInstitution;
    private Label[] lblCountry;
    private TextBox[] txtCountry;
    private Label[] lblEmail;
    private TextBox[] txtEmail;
    private PlaceHolder PlaceHolder1;


    public int NumberOfOtherAuthors()
    {
        Int32 index = Convert.ToInt32(NumberList.SelectedValue);
        return index;
    }

    public void GUIofOtherAuthor()
    {
        int authors;
        int i = 0;
        int j = 1;


        authors = NumberOfOtherAuthors();
        lblName = new Label[authors];
        txtName = new TextBox[authors];
        lblSurname = new Label[authors];
        txtSurname = new TextBox[authors];
        lblInstitution = new Label[authors];
        txtInstitution = new TextBox[authors];
        lblCountry = new Label[authors];
        txtCountry = new TextBox[authors];
        lblEmail = new Label[authors];
        txtEmail = new TextBox[authors];
        PlaceHolder1 = new PlaceHolder();


        for (i = 0; i < authors; i++)
        {
            Label authorInformation = new Label();
            authorInformation.Text = "Information for Author " + j.ToString() + " :";

            lblName[i] = new Label();
            lblName[i].Text = "Name:";
            txtName[i] = new TextBox();
            lblSurname[i] = new Label();
            lblSurname[i].Text = "Surname:";
            txtSurname[i] = new TextBox();
            lblInstitution[i] = new Label();
            lblInstitution[i].Text = "Institution:";
            txtInstitution[i] = new TextBox();
            lblCountry[i] = new Label();
            lblCountry[i].Text = "Country:";
            txtCountry[i] = new TextBox();
            lblEmail[i] = new Label();
            lblEmail[i].Text = "Email:";
            txtEmail[i] = new TextBox();

            PlaceHolder1.Controls.Add(new LiteralControl("<table>"));
            PlaceHolder1.Controls.Add(new LiteralControl("<span style=\"font-weight:bold;\" "));
            PlaceHolder1.Controls.Add(authorInformation);
            PlaceHolder1.Controls.Add(new LiteralControl("</span>"));
            PlaceHolder1.Controls.Add(new LiteralControl("<tr><td>"));
            PlaceHolder1.Controls.Add(lblName[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td><td>"));
            PlaceHolder1.Controls.Add(txtName[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td></tr>"));
            PlaceHolder1.Controls.Add(new LiteralControl("<tr><td>"));
            PlaceHolder1.Controls.Add(lblSurname[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td><td>"));
            PlaceHolder1.Controls.Add(txtSurname[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td></tr>"));
            PlaceHolder1.Controls.Add(new LiteralControl("<tr><td>"));
            PlaceHolder1.Controls.Add(lblInstitution[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td><td>"));
            PlaceHolder1.Controls.Add(txtInstitution[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td></tr>"));
            PlaceHolder1.Controls.Add(new LiteralControl("<tr><td>"));
            PlaceHolder1.Controls.Add(lblCountry[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td><td>"));
            PlaceHolder1.Controls.Add(txtCountry[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td></tr>"));
            PlaceHolder1.Controls.Add(new LiteralControl("<tr><td>"));
            PlaceHolder1.Controls.Add(lblEmail[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td><td>"));
            PlaceHolder1.Controls.Add(txtEmail[i]);
            PlaceHolder1.Controls.Add(new LiteralControl("</td></tr>"));
            PlaceHolder1.Controls.Add(new LiteralControl("</table><br /> "));
            Panel1.Controls.Add(PlaceHolder1);

            j++;
        }
    }

Now i want to take the value of textboxes in another function public void UploadForm(){...}. I try it

int i;
int numberOfOtherAuthors = NumberOfOtherAuthors();

for(i=0; i<numberOfOtherAuthors; i++)
{
   String a = txtname[i].text
}

The Textboxes values I want to upload to the database, but let's say we save them to a string. When i do this, i have the NullReferenceException. So how to get the value of this textboxes??? Thanks

Answer 1

I noticed that your UploadForm() function is referencing txtname, while your actual TextBox is declared as txtName. Since field names are case-sensitive, the field "txtname" (lower-case 'n') is not actually defined, so it is probably the cause of your NullReferenceException in your dynamic page.