Bizarre question in CS intro class

[MouthBreather]

Part of my intro to CS class is access to "my programming lab" which is a collection of questions relating to the text. This question is supposed be related to section 6.1 of Savitch's "Problem Solving with C++". The section is titled "Why use files for I/O?" and has nothing to do with strings. I can't find any mention of anything like this in the text, anywhere. Since I'm new to C++, I could just be missing the key words.

The question:

Which string does NOT match the regular expression: "v.x.*"?

v.x.*
vx
v.x
vxxxxxxx
vvx

Through trial and error I get the answer to be "vx". I do not understand this at all from my experience with wildcards in DOS, Unix, etc. Please educate me!

Jim

[MouthBreather]

Wow no one has an idea what this question is about huh?

[TarikNeaj]

You could email your Professor to clarify the question or ask a class mate.

[Duthomhas]

This question has nothing to do with files or I/O.
In a very technical sense, it does have to do with strings, but not c-strings or std::string.

The question is specifically about regular expressions, which you should spend some time reading about. Pretty good introductions can be found at http://regexone.com/ and http://www.bsd.org/regexintro.html.

You are correct, because v.x.* requires a minimum of three characters to match.

The first character must be a 'v'. v
The second character can be anything. .
The third character must be an 'x'. x
Zero or more of any characters may follow. .*

Hope this helps.

[MouthBreather]

Thanks Duoas, the answer must be wrong.

[Duthomhas]

No, I agreed that your answer was correct, because it has only two characters. Please read carefully.