Adding controls to panel

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Hi Below is my code I am getting format exception error
Input string was not in a correct format. In design page i have drop-down when i select number from dropdown it has to create that many text box controls

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace Panel2
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            int[] numbers = { 1, 2, 3, 4, 5, 6 };
            ddlNumbers.DataSource = numbers;
            ddlNumbers.DataBind();
            ddlNumbers.Items.Insert(0, "--Select--");

        }

        protected void ddlNumbers_SelectedIndexChanged(object sender, EventArgs e)
        {

            for (int i = 0; i < int.Parse((ddlNumbers.SelectedItem.Text)); i++)
            {


                Panel1.Visible = true;
                TextBox tx = new TextBox();
                tx.ID = "tx" + i.ToString();
                Panel1.Controls.Add(tx);
                Literal lt = new Literal();
                lt.ID = "lt" + i.ToString();
                lt.Text = "<br/>";
                Panel1.Controls.Add(lt);

            }
        }
    }
}

Posted 23-Oct-15 3:19am

ShaHam11

Updated 23-Oct-15 3:23am

v2

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Krunal Rohit 23-Oct-15 9:29am

int.Parse((ddlNumbers.SelectedItem.Text.ToString()))

-KR

ShaHam11 23-Oct-15 9:36am

Still the same error infact I tried selectedItem value still the same error

CHill60 23-Oct-15 9:59am

What is the selected text?

Richard Deeming 23-Oct-15 10:05am

NB: The Text property is already a string; there's no need to call .ToString() on it! :)

CHill60 23-Oct-15 10:06am

Virtual 5 - I'll confess it's a mistake I still keep making :facepalm:

2 solutions

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Richard Deeming · Accepted Answer · 2015-10-23T04:11:00

Try:

C#

protected void ddlNumbers_SelectedIndexChanged(object sender, EventArgs e)
{
    int count;
    string text = ddlNumbers.SelectedItem.Text;
    if (!int.TryParse(text, out count))
    {
        Trace.Warn("Numbers", string.Format("Cannot parse '{0}' as an integer.", text));
    }
    
    for (int i = 0; i < count; i++)
    {
        ...

Turn on page-level tracing (<%@ Page Trace="True" ... %>) and look for the warning message, which will tell you what value it's failing to parse.

You'll also want to wrap your binding code in a if (!IsPostBack) { ... } block. At the moment, you're re-binding the list every time the page posts back to the server.

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        BindNumbersList();
    }
}

private void BindNumbersList()
{
    int[] numbers = { 1, 2, 3, 4, 5, 6 };
    ddlNumbers.DataSource = numbers;
    ddlNumbers.DataBind();
    ddlNumbers.Items.Insert(0, "--Select--");
}

ShaHam11 · Accepted Answer · 2015-10-23T04:32:00

Solution 2

I found the soultion I just commented this line ddlNumbers.Items.Insert(0, "--Select--");

when i debug add it in the watch I get --select-- after

Posted 23-Oct-15 4:32am