How to dynamically create textbox in asp.net c# on button click according to user input value?

You can create and get the value of dynamically created text box in asp.net web forms using the below code

Web-forms .aspx HTML code

<asp:Panel ID="pnlTextBoxes" runat="server">
</asp:Panel>
<hr />
<asp:Button ID="btnAdd" runat="server" Text="Add New" OnClick="AddTextBox" />
<asp:Button ID="btnGet" runat="server" Text="Get Values" OnClick="GetTextBoxValues" />

C# Code behind

//retain the dynamic TextBoxes across PostBacks
protected void Page_PreInit(object sender, EventArgs e)
{
    List<string> keys = Request.Form.AllKeys.Where(key => key.Contains("txtDynamic")).ToList();
    int i = 1;
    foreach (string key in keys)
    {
        this.CreateTextBox("txtDynamic" + i);
        i++;
    }
}

protected void AddTextBox(object sender, EventArgs e)
{
    int index = pnlTextBoxes.Controls.OfType<TextBox>().ToList().Count + 1;
    this.CreateTextBox("txtDynamic" + index);
}
 
private void CreateTextBox(string id)
{
    TextBox txt = new TextBox();
    txt.ID = id;
    pnlTextBoxes.Controls.Add(txt);
 
    Literal lt = new Literal();
    lt.Text = "<br />";
    pnlTextBoxes.Controls.Add(lt);
}


//Get Value of textbox
protected void GetTextBoxValues(object sender, EventArgs e)
{
    string message = "";
    foreach (TextBox textBox in pnlTextBoxes.Controls.OfType<TextBox>())
    {
        message += textBox.ID + ": " + textBox.Text + "\\n";
    }
    ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('" + message + "');", true);
}

The above code Adds textbox dynamically, and get it's value 

Few more links which may help

1.http://sunilgurjaraspdotnet.blogspot.in/2012/07/add-dynamic-controlstext-box_3.html (To add Textbox, Dropdown list, radio button and checkbox)

2. https://www.codeproject.com/Questions/453289/How-to-dynamically-create-textboxes-in-asp-net-and

3. http://crazygeeksblog.com/2014/02/c-net-dynamically-create-textbox-in-asp-net/

4. http://www.dotnetspark.com/kb/1368-create-and-retrieve-value-from-dynamic-controls.aspx

5. http://www.itprotoday.com/web-development/manage-dynamically-created-controls

6. http://www.nullskull.com/q/10299810/how-can-i-add-labels-and-textbox-to-aspx-page-dynamically.aspx

Hope this helps, thanks