Customize regular expression to allow alphabets and dots in textbox

Hello friends In my application I want to customize regular expression in such a way that it will allow character and dot only. For eg. I could be be able to enter M.C.A or MCA any of these. For this ta开发者_C百科sk how to customize regular expression? I tried [a-zA-Z] followed by\ and dot in side bracket but is not working. I also tried [ABCD] just for testing but it shows invalid text for ABC. What might be the reason???? Thanks to all...

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You will need to escape the dot as in regex it normally means 'any character'

[a-zA-Z\.]+

in c# you will need to deinfe the regex string as follows:

var r = @"[a-zA-Z\.]+";

Edit based on comment:

<asp:TextBox ID="qualificationBox" runat="server" Width="250px"></asp:TextBox>
<asp:RegularExpressionValidator ID="NameRequiredValidator" runat="server" 
 ErrorMessage="Please Enter Name" ControlToValidate="qualificationBox" 
 ValidationExpression="[a-zA-Z\.]+"></asp:RegularExpressionValidator>

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You may need to double escape the backslash:

[a-zA-Z\\.]+