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ASP.NET Tutorial - User Controls

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The following table lists the types of validation controls available and how you can use them.

Type of validation

Control to use

Description

Required entry

RequiredFieldValidator

Ensures that the user does not skip an entry.

Comparison to a value

CompareValidator

Compares a user's entry against a constant value, or against a property value of another control, using a comparison operator (less than, equal, greater than, and so on).

Range checking

RangeValidator

Checks that a user's entry is between specified lower and upper boundaries. You can check a range within pairs of numbers, alphabetic characters, and dates.

Pattern matching

RegularExpressionValidator

Checks that the entry matches a pattern defined by a regular expression. This type of validation allows you to check for predictable sequences of characters, such as those in social security numbers, e-mail addresses, telephone numbers, postal codes, and so on.

User-defined

CustomValidator

Checks the user's entry using validation logic that you write yourself. This type of validation allows you to check for values derived at run time.

Let us see an example of above controls.

Example 14 RequiredFieldValidator.aspx

Sub Button_Click( s As Object, e As EventArgs )

If IsValid Then

Response.Redirect (“Thanks.aspx”)

End If

End Sub

</Script>

<html>

<head><title>RequiredFieldValidator.aspx</title></head>

<body>

Username:

<br><asp:TextBox

ID="txtUsername"

Runat="Server" />

<asp:RequiredFieldValidator

ControlToValidate="txtUsername"

Text="You must enter a username!"

Runat="Server" />

<p>

Password:

<br>

<asp:TextBox

id="txtComments"

Runat="Server"/>

<asp:RequiredFieldValidator

ControlToValidate="txtComments"

Text="You must enter some comments!"

Runat="Server" />

<p>

<asp:Button

Text="Submit"

OnClick="Button_Click"

Runat="Server"/>

</form>

</body>

</html>

The output of this example is shown below:

In this example if we do not enter the vales into the textboxes and submit the form then the RequiredFieldValidator controls displays error message and the IsValid property has the value false. Otherwise, the Button_Click subroutine automatically redirects you to a page named Thanks.aspx

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