Does an empty string contain an empty string in C++?

Question

Just had an interesting argument in the comment to one of my questions. My opponent claims that the statement \"\" does not contain \"\"<

Answer 1

It depends on what you mean by "contains".

The empty string is a substring of the empty string, and so is contained in that sense.

On the other hand, if you consider a string as a collection of characters, the empty string can't contain the empty string, because its elements are characters, not strings.

Relating to sets, the set

{2}

is a subset of the set

A = {1, 2, 3}

but {2} is not a member of A - all A's members are numbers, not sets.

In the same way, {} is a subset of {}, but {} is not an element in {} (it can't be because it's empty).

So you're both right.