IF statement for Search Filter in AD

   if (username.Contains("."))
                {
                    string Fname = username.Substring(0, username.IndexOf("."));
                    Fname = Fname.Replace(" ", "");
                    
                    string[] splitString = username.Split(new char[] { '.' });
                    username = splitString[splitString.Length - 1];


//*****Am trying to write IF statement here like this but need some help to complete this if statement.


              If (search.Filter = "(sn=" + username + ")&(givenname=" + Fname + ")";
			
			search.Filter = "(sn=" + username + ")";


}