how to create validation control in asp.net with example.

ASP.Net validation controls validate the user input data to ensure that useless, unauthenticated or contradictory data don’t get stored.

ASP.Net provides the following validation controls:

1. RequiredFieldValidator
2. RangeValidator
3. CompareValidator
4. RegularExpressionValidator
5. CustomValidator
6. ValidationSummary

1. RequiredFieldValidator: The RequiredFieldValidator control ensures that the required field is not empty. It is generally tied to a text box to force input into the text box.

The syntax for the control:

<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" 

            ControlToValidate="TextBox1" ErrorMessage="must enter name">

            </asp:RequiredFieldValidator>

2. Range Validator:The RangeValidator control verifies that the input value falls within a predetermined range.

The syntax for the control:

 <asp:RangeValidator ID="RangeValidator1" runat="server" 

                ControlToValidate="TextBox4" ErrorMessage="not in range" 

                MaximumValue="12/12/12" MinimumValue="11/11/11" Type="Date"></asp:RangeValidator>

It has three specific properties:

Properties	Description
Type	it defines the type of the data; the available values are: Currency, Date, Double, Integer and String
Minimum Value	it specifies the minimum value of the range
Maximum Value	it specifies the maximum value of the range

3. The Custom Validator:The CustomValidator control allows writing application specific custom validation routines for both the client side and the server side validation.

The client side validation is accomplished through the ClientValidationFunction property. The client side validation routine should be written in a scripting language, like JavaScript or VBScript, which the browser can understand.

The server side validation routine must be called from the control.s ServerValidate event handler. The server side validation routine should be written in any .Net language, like C# or VB.Net.

The basic syntax for the control

<asp:CustomValidator ID="CustomValidator1"        runat="server"        ClientValidationFunction=.cvf_func.        ErrorMessage="CustomValidator"> </asp:CustomValidator>