Give validation to textbox that accepts min 6 charecters and max 12 charecters in Asp.net

For that add textbox control with the property MaxLength=12 and add RegularExpressionValidator with RegularExpression.

<asp:TextBox ID="TxtName" runat="server" MaxLength="12" Width="200px"></asp:TextBox>

<br />

<asp:RegularExpressionValidator

ID="RegularExpressionValidator1" 

ControlToValidate="TxtName"                                

ValidationExpression="(?=^.{6,12}$)(?=.*\d)(?=.*\W+)(?![.\n]).*$"

runat="server"

Text="Password must have minimum 6 characters & maximum 12 characters"></asp:RegularExpressionValidator>