Inside code, code blocks and inline code, QuickBook does not allow any markup to avoid conflicts with the target syntax (e.g. c++). In case you need to switch back to QuickBook markup inside code, you can do so using a language specific escape-back delimiter. In C++ and Python, the delimiter is the double tick (back-quote): "``" and "``". Example:

void foo()
{
}

Will generate:

void foo()
{
}

When escaping from code to QuickBook, only phrase level markups are allowed. Block level markups like lists, tables etc. are not allowed.