how to display alert box in asp.net

Question

i have a registration page with a submit button.

i want to show an alert box when the \"user clicks on the submit button\" after which the \"data entered by the user

Answer 1

Regular Page

public void ErrorTrap(string str)
{
   Page.ClientScript.RegisterStartupScript(this.GetType(), "alert" + UniqueID, 
     "alert('" + str + "');", true);
}

Ajax Page

You need to use ScriptManager if you use ajax.

public void ErrorTrap(string str)
{
   ScriptManager.RegisterStartupScript(Page, Page.GetType(), "alert" + UniqueID, 
      "alert('" + str + "');", true);
}