Are C# 4.0 books out of date?

Question

C++ / C#

There is already sharp 8.0, so are the books about sharp 4.0 out of date?

Answer 1

Already have the 9th.
Outdated, of course.
Read (+ history of previous versions).

Answer 2

Is the wheel old?
After all, he is thousands of years old.
I'm looking at a wheel that came out in 2020, it's round with nanotech trajectors
Should I think about studying a wheel in 2020?

Answer 3

For the most part, no, all subsequent versions are syntactic sugar.

Answer 4

See what book. If it only talks about the syntax of the language, then most likely you need to take something newer. For example, the official docks as the most up-to-date source.
On the other hand, there haven't been any particularly fundamental changes since version 4.5.
Therefore, such books about dotnet as:
- Jeffrey Richter: CLR via C# 4th edition
- John Skeet: C# for professionals (C# in Depth) 3rd edition
can be read and even recommended. Just keep in mind that the above books are not for beginners.
For beginners, Troelsen or Albahari are probably suitable