New library CStringBuilder to print content to a c-string

I was pointing out that there are an apparent discrepancy between the code and the output. That is either because the output was not from the posted code or because the posted code is doing something wrong.

It is up to you to explain which is true, and, if it was a problem with the library, to say that and to post the corrected output.

I'm not going to use a library that has apparent bugs.