Question

I have a HTML input box in my ASPX page like below

<input id="txtID" runat="Server" type="text" />

Now I have some code written in C# codebehind which calculate a value and I want that value to be displayed in the above TextBox.

I have already tried

txtID.Value = Number.ToString();

and

HtmlGenericControl ct = new HtmlGenericControl();
ct.InnerHTML = Number.ToString();
txtID.Controls.Add(ct);

but both of the above does not seems to set the display text of the textbox.

Can anyone help me figure out as to how do I get it done.
I cannot use

<asp:TextBox />

EDIT (WITH CORRECT ANSWER):
The way I was originally trying to do was correct i.e.

txtID.Value = Number.ToString();

The culprit was Placeholder Plugin which was getting called and was erasing the values from the TextBox. Hope this will help a lot of people like me who get stuck at such silly places.

Answer 1

You can change value of control by injecting Javascript on PageLoad or PageInit. Just say GetValueDummy() method is your method to calculate a value and you are using jQuery.

You need to inject a javascript to page in Page.Load handler.

protected void Page_Load(object sender, EventArgs e)
{
    var script = "$('#txt').val('" + GetValueDummy() + "');";
    ClientScript.RegisterStartupScript(typeof(string), "textvaluesetter", script, true);
}

In this code, txt is id of your input.

If you are not using jQuery just replace value of script variable to

var script = "document.getElementById('txt').value = '" + GetValueDummy() + "';";

After some point your page will be fully rendered and ready to send to client. So you cant directly modify it from c#. You can read more about page life time here: http://msdn.microsoft.com/en-us/library/ms178472.aspx