*According to the C++11 standard*, is the behaviour of 

```
ifstream in(".");

```

specified, or is it system-dependent?

For context, I'm trying to avoid using `boost::filesystem` and similar libraries because they cause unrelated portability problems.

Edit: According to what I can find, I should get a valid ifstream (one that is 'good()' if and only if the directory exists. This potentially gives a more portable way of testing whether a directory exists than using `boost::filesystem` because the latter requires you to link against more libraries.