asp.net file control

The ASP.NET Framework (version 3.5) contains over 70 controls. These controls can be divided into seven groups:

Ø  Standard Controls : The standard controls enable you to render standard form elements such as buttons, input fields, and labels.

Ø  Validation Controls : The validation controls enable you to validate form data before you submit the data to the server. For example, you can use a RequiredFieldValidator control to check whether a user entered a value for a required input field.

Ø  Rich Controls : The rich controls enable you to render things such as calendars, file upload buttons, rotating banner advertisements, and multi-step wizards.

Ø  Data Controls : The data controls enable you to work with data such as database data. For example, you can use these controls to submit new records to a database table or display a list of database records. Navigation Controls. The navigation controls enable you to display standard navigation elements such as menus, tree views, and bread crumb trails.

Ø  Login Controls : The login controls enable you to display login, change password, and registration forms.

Ø  Web Part Controls :The Web Part controls enable you to build personalizable portal applications.

Ø  HTML Controls : The HTML controls enable you to convert any HTML tag into a server-side control.

·         With the exception of the HTML controls, you declare and use all the ASP.NET controls in a page in exactly the same way. For example, if you want to display a text input field in a page, then you can declare a TextBox control like this:

               <asp:TextBox id="TextBox1" runat="Server" />

·         This control declaration looks like the declaration for an HTML tag. Remember, however, unlike an HTML tag, a control is a .NET class that executes on the server and not in the web browser.

·         When the TextBox control is rendered to the browser, it renders the following content:

               <input name="TextBox1" type="text" id="TextBox1" />

·         The first part of the control declaration, the asp: prefix, indicates the namespace for the control. All the standard ASP.NET controls are contained in the System.Web.UI.WebControls namespace. The prefix asp: represents this namespace.Next, the declaration contains the name of the control being declared. In this case, a TextBox control is being declared.

·         This declaration also includes an ID attribute. You use the ID to refer to the control in the page within your code. Every control must have a unique ID.