Question

How to allow user to enter only 0 or 1 in the textbox.I am using C#.net. Textbox has maxlength is 1.I am want to add validation expression in regular expression.I don’t want use javascript.

Answer 1

I understand the question in the following way:

you don’t want to use javascript only to prevent that the users enters something else than 0 or 1 but a validator which can be used on client- and on serverside.

I would use a RangeValidator with Type="Integer" and appropriate MinimumValue and MaximumValue instead.

<asp:RangeValidator id="Range1"
           ControlToValidate="TextBox1"
           MinimumValue="0"
           MaximumValue="1"
           Type="Integer"
           EnableClientScript="false"
           Text="The value must be from 0 to 1!"
           runat="server"/>

Note: If the input control is empty, no validation functions are called and validation succeeds. Use a RequiredFieldValidator control to prevent the user from skipping an input control.

As other have mentioned, a CheckBox might be more appropriate for this task.