Question

Possible Duplicate:
ASP.NET TextBox filter

If i have a textbox and i want to add a validation too it, how can i then add a validation, so i Only can write some letters, maybe T, K, or U or Empty !? so other letters like G,f,d,s Can’t be used !?

Answer 1

You make a regular expression validator and supply a regular expression for what letters you want.

Such as letters only is:

<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ErrorMessage="RegularExpressionValidator" ControlToValidate="TextBox1" ValidationExpression="[aA-zZ]"></asp:RegularExpressionValidator>