C# Console and GUI Application in one

This is in delay to my surpassing doubt here myPost. That was a kind of a
call question. Somehow we will cgange that in Java and use it.To pierce
further, we have solid to re-do that digest in C# that we am some-more
peaceful with. To start with we strike a roadblock. In that java
application, a tangible coding is finished in Eclipse and a .jar can be
executed by management line. Also a GUI is finished controlling Netbeans
that refers to a tangible way in Eclipse. So a same appl is used as a
management line as good as GUI.How can we do this in C# ?? Just write a
formula once and afterwards govern .exe or by GUI, though both will work
independently.