Q:

A question seeking for factual answer wrongly closed as "Off-topic/MCVE"

Refer to this question: How many digits of the double type can survive when going from C# to C++? 
It was closed for the reason "Off-topic":

"Questions seeking debugging help ("why isn't this code working?")
  must include the desired behavior, a specific problem or error and the
  shortest code necessary to reproduce it in the question itself.
  Questions without a clear problem statement are not useful to other
  readers. See: How to create a Minimal, Complete, and Verifiable
  example." – Hans Passant, Alan Birtles, Narendra Jadhav, mag_zbc, Rob

What?
This is not a question seeking debugging help-- in fact it is asking a factual question, and has a factual answer.
Ironically one of the comments actually gives the answer, and suggests a solution. So it is answerable, and is not off-topic. If the comment was posted as an answer, I would have prepared to accept it.
And I do think the question is phrased in such a way that will help incoming visitors from Google Search Engine. 
Edit 1: I've edited the question to explicitly asked the user to not solve my code.
Edit 2: Someone brings up my 500+ questions history, so it is only fitting for me to elaborate on this here. If you compare my early questions vs. my lately questions, my early questions tend to receive better answers and more upvotes in general, despite that they were not necessarily better written than my current ones. I would even say that my early questions were worse-off, but the early SOers were a lot more helpful and forgiving, and tended to answer the question from an answerable angle, instead of nitpicking and finding ( very hard) an interpretation that would render the question unanswerable and then proceed to close it as "Off topic". 
My question history, instead of reminds me how to write good questions, actually reminds everyone how far SO has (d)evolved in the direction of increasing unhelpfulness, hostility, nitpicking and unforgiving lately. 

A:

Quoting the core of your question:

How many digits of the double type can survive when going from C# to C++?
Let's say if I pass a double from C# to C++, how many digits of the double will be preserved?

As I see it, there are two ways of interpreting it:

As a question about the specs of the double types in C# and C++. Given the background context provided by the remarks about your interop code, that looks a little like a XY problem, but that isn't grounds for closure. Under this interpretation, "Off-topic/MCVE" wouldn't apply.

As a question about to which extent interop code will preserve information when you "pass a double from C# to C++". Under this interpretation, "Off-topic/MCVE" does apply, as the answer depends specifically on what your interop code is doing.

(As an additional wording quibble, the "can survive" phrasing in the title suggests #1 , while "will be preserved" in the question body suggests #2.)
When I began to write this answer, I was strongly leaning towards #1; another look at the question, though, has made #2 feel quite reasonable. On the other hand, your remarks about Hans' comment suggest you consider #1 to be more in line with what you originally meant. Perhaps editing the question to make that clearer (e.g. by retrofitting it to better match Hans' comment) would help.

