[regex] Minimum 6 characters regex expression

I m looking for regex which checks for at least 6 characters, regardless of which type of character.

If I understand correctly, you need a regex statement that checks for at least 6 characters (letters & numbers)?

/[0-9a-zA-Z]{6,}/

Something along the lines of this?

<asp:TextBox id="txtUsername" runat="server" />

<asp:RegularExpressionValidator
    id="RegularExpressionValidator1"
    runat="server"
    ErrorMessage="Field not valid!"
    ControlToValidate="txtUsername"
    ValidationExpression="[0-9a-zA-Z]{6,}" />