C# textbox char only??

is there a really simple way of denying creation of a file/account if it contains anything other than a character/letter (no symbols or numbers)


for example:-


IF login.textbox is all characters
Create New Account

ELSE

display message " Invalid name, please try again (a-z only) "


i looked on google and people's code is really messy and untidy, (couldn't understand it)

can anyone help me code this tiny bit of verification?


thanks a bunch!

'Chris

 

for real?

here. drop this in a webform.. just to test.

Code:

  <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="TextBox1"
            ErrorMessage="RegularExpressionValidator" ValidationExpression="[a-zA-Z]+">*</asp:RegularExpressionValidator>
        <br />
        <asp:Button ID="Button1" runat="server" Text="Button" />