Which function pair in QString to use for converting to/from std::string?

I'm working on a project that we want to use Unicode and could end up in countries like Japan, etc... We want to use std::string for the underlying type that holds string data in the data layer (see Qt, MSVC, and /Zc:wchar_t- == I want to blow up the world as to why). The problem is that I'm not completely sure which function pair (to/from) to use for this and be sure we're 100% compatible with anything the user might enter in the Qt layer.

A look at to/fromStdString indicates that I'd have to use setCodecForCStrings. The documentation for that function though indicates that I wouldn't want to do this for things like Japanese. This is the set that I'd LIKE to u开发者_StackOverflowse though. Does someone know enough to explain how I'd set this up if it's possible?

The other option that looks like I could be pretty sure of it working is the to/fromUTF8 functions. Those would require a two step approach though so I'd prefer the other if possible.

Is there anything I've missed?

The documentation is a bit disconcerting here (on QString). However, the docs on QTextCodec don't seem to note any problems. It does however return QByteArray instead of a std::string. You can of course easily convert QByteArray to a std::string. But if you look at the source for QString you'll see that toStdString does exactly that:

inline std::string QString::toStdString() const
{ const QByteArray asc = toAscii(); return std::string(asc.constData(), asc.length()); }

toAscii in turn will use whatever codec has been set with QTextCodec::setCodecForCString.

Their warning about the Japanese codec is likely valid, however, if your OS is using the Japanese codec you likely won't have a problem. I'm not entirely sure here.

But you can avoid that problem. Simply set your codec as UTF-8 and then toStdString should convert everything into UTF-8. In fact I'm going to do that with my code right now. :)