C# .NET - comparing two string using regular expression

Hi All,

I have a password requirement change box for the users in asp.net. I am trying to write a regular expression where the four characters of the old passoword should not be same as the four characters of the new password string in C#. The code should return false if they are same.

Can I do this in regular expression, if not, is their any other quick way

Thanks.

How about this one

1. Compare the length of the strings and if they are equal then it is a valid password else not


untested

protected bool validpassword(string newpassword, string oldpassword)
{
   if(newpassword.Trim().Length() == oldpassword.Trim().Length() )
    {
     return true;
    }
   else
    {
   return false;
    }
}