casting

Greetings, I am in a need to extend a class to add few new methods/properties that base class lacks. so, i have created a class that extend another class. but issue arises when i need to covert/cast base class to derived class. it doesn't works. so? is i am doing it wrong, or it's not...

I'm trying to save the Outlook attachment file email and save in sql. I tried this following code and it only saved a numerical values using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Data.SqlClient; using...

Since List<> is just a wrapper around an array why can't I supply the array through the constructor? It only allows a collection which is relatively expensive opposed to just handing it an array directly.