Validation Expression for asp.net - asp.net

Question

I need to validate textbox value for a password, on client-side.
I want to use RegularExpressionValidator.
Please provide me, the value for 'VALIDATION EXPRESSION'for following two conditions:-
"Password should contain minimum of 8 characters"
"Password should ahve atleast one non -alphanumeric character"
<asp:RegularExpressionValidator
ID="PasswordFormatValidator"
runat="server" Display="Dynamic"
ErrorMessage="Invalid Password Format"
ValidationExpression="??????????????"
ControlToValidate="txtEmail">Invalid Email Format
</asp:RegularExpressionValidator>
Or shall I use Custom Validator. If so, please provide the expression for the req condition.

Answer 1

Here is lots of information about this asp control which demonstrate about the regular expression and how setup ValidationExpression.
Visit MSDN:RegularExpressionValidator Control
for example:
<asp:RegularExpressionValidator id="RegularExpressionValidator1"
ControlToValidate="TextBox1"
ValidationExpression="\d{5}"
Display="Static"
EnableClientScript="false"
ErrorMessage="Zip code must be 5 numeric digits"
runat="server"/>
check this also for more information:
Use Regular Expressions to Constrain Input in ASP.NET
Password
ValidationExpression="(?!^[0-9]*$)(?!^[a-zA-Z]*$)^([a-zA-Z0-9]"{8,10})$
Validates a strong password. It must be between 8 and 10 characters, contain at least one digit and one alphabetic character, and must not contain special characters.
if you just want to check length must be minimum.(atleast 1) can contain any value. you can replace 1 to check any minimum length of password.
ValidationExpression=".{1,}"