You can call the private constructor from the public constructor. Another version of the same thingIt is possible to use a private constructor from within the class. In an abstract class, that is probably only useful if called from a non-private constructor. Agreed, it is not something you will want at all frequently.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com