Checking for the control type

I am able to get the IDs of all the controls of a page and also their type, in the page when i print it it shows

myPhoneExtTxt Type:System.Web.UI.HtmlControls.HtmlInputText

this is generated based on this code

    foreach (Control c in page)
    {
        if (c.ID != null)
        {
            controlList.Add(c.ID +" Type:"+ c.GetType());
        }
    }

But now i need to check its type and access the text in it if its of type HtmlInput and i am not quite sure how to do that.

Like

if(c.GetType() == (some htmlInput))
{
   some htmlInput.Text = "This should be the new text";
}

how can i do this, i think you get the idea?.