Setting up a C# .Net program

When you create a new project at the top of the form is a combo box - in that is the target framework (eg. .Net Framework 4).

If you have an existing project then in the solution view right click the project and choose properties from the menu.  In the tab view select Application and there is target framework in a combobox eg. .Net Framework 4

So if I setup for .Net version 4.0 will it still work with 4.5?

Yes. It does work "if" you do not use 4.5 Functions and features in your code.

An example is SortVersion class which belongs to 4.5 only.

If you set up for .Net 4.0 and use SortVersion class in your code you get compile error.

So if I set 4.0 I can only stuff related to 4.0 and can I assume backward compatible correct?

Thank you